SECOND AMENDMENT TO THE REVOLVING CREDIT LOAN AGREEMENT

Exhibit 10.1

SECOND AMENDMENT

SECOND AMENDMENT dated as of December 1, 2006 (this " Second Amendment ") by and among HARVARD BIOSCIENCE, INC., a Delaware corporation (the " Borrower "); the lenders identified on the signature pages hereto (individually, a " Lender " and collectively, the " Lenders "); and Brown Brothers Harriman & Co., as agent for the Lenders (in such capacity, together with its successors in such capacity, the " Agent ").

The Borrower, the Lenders and the Agent are parties to a Revolving Credit Loan Agreement dated as of November 21, 2003 (as amended by a First Amendment dated March 14, 2006 and heretofore modified and in effect on the date hereof, the " Loan Agreement "), pursuant to which the Lenders have agreed to make certain revolving credit loans to the Borrower. The Borrower, Lenders and Agent wish to extend the maturity date under the Loan Agreement to December 1, 2009 and amend the Loan Agreement in certain other respects, all on the terms and conditions hereinafter set forth.

NOW, THEREFORE, in consideration of the foregoing and the mutual covenants herein contained, and for other good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, the parties signatory hereto agree as follows:

1. Definitions . Except as otherwise defined in this Second Amendment, terms defined in the Loan Agreement are used herein as defined therein.

2. Amendments . Subject to the satisfaction of the conditions precedent specified in Section 4 below, but effective as of the date hereof, the Loan Agreement shall be amended as follows:

(a) In order to give effect to the extension of the Maturity Date,

• (i) the first sentence of Section 1.1 of the Loan Agreement shall be amended to read in its entirety as follows:

  "1.1. Recitals; Maximum Line Commitment . The Borrower wishes to establish a revolving credit facility (the " Line of Credit ") with the Lenders in an aggregate principal amount at any one time outstanding not in excess of Twenty Million Dollars ($20,000,000) (the " Maximum Line Commitment "), to expire December 1, 2009 (the " Maturity Date ");" and

  (ii) the definition of Maturity Date appearing in Section 9 of the Loan Agreement is hereby amended by deleting such definition in its entirety, and inserting in lieu thereof the following:

  " Maturity Date : has the meaning specified in subsection 1.1."

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(b) Section 1.2(b) Mechanics of Revolving Credit Loans is hereby deleted in its entirety and the following is inserted in lieu thereof:

• (b) Mechanics of Revolving Credit Loans . Each Revolving Credit Loan shall be made by the Lenders, severally in accordance with their respective Commitments and in such amounts (not in excess of the Maximum Line Commitment) as the Borrower shall request. Revolving Credit Loans shall be effected at the principal banking office of the Agent at 40 Water Street, Boston, Massachusetts 02109-3661, and shall be made at such times as the Borrower may request upon one (1) Banking Day’s prior notice to the Agent in the case of any borrowing for which interest is calculated using the Base Rate (collectively, " Base Rate Loans ") and three (3) Banking Days’ prior notice in the case of any borrowing (x) for which interest is calculated using the LIBOR Rate (collectively, "LIBOR Portions") or (y) which is borrowing in Eurocurrency. Each borrowing request for the Revolving Credit Loans which are not in Eurocurrency shall be in the form attached hereto as Exhibit E (the " Borrowing Request "). Each borrowing request for a Eurocurrency Loan ("Eurocurrency Borrowing Request") shall be in the form required in Section 1.2(d)(2) below. Each Borrowing Request and each Eurocurrency Borrowing Request may be sent to the Agent by facsimile. The Lenders will use their best efforts to fund requests for Revolving Credit Loans on the Banking Day requested by the Borrower in accordance with the terms hereof. In the event that notwithstanding its best efforts, the Lenders are unable to fund a requested Revolving Credit Loan on the Banking Day requested by the Borrower in accordance with the terms hereof, the Lenders shall have no liability whatsoever for such failure to fund on the requested Banking Day and will fund such Revolving Credit Loan (a) on the next Banking Day in the case such Revolving Credit Loan accrues interest based upon the Base Rate or the LIBOR Rate and (b) if possible on the next Banking Day in the case of Eurocurrency Loans. The Lenders shall make each Revolving Credit Loan which is not a Eurocurrency Loan hereunder by crediting the amount of such Revolving Credit Loan to the Borrower’s operating account (Account No. 8142333) with the Agent (together with any other account from time to time designated by the Borrower for the purpose of effecting Revolving Credit Loans, the " Operating Account "). The Lenders shall make each Revolving Credit Loan which is a Eurocurrency Loan hereunder by crediting the amount of such Eurocurrency Loan, in the Eurocurrency requested, to the applicable Eurocurrency demand deposit account with the Agent.

(c) Section 1.2 Revolving Credit Loans; Reborrowings; Compliance Certificates is hereby amended by adding the following section:

• • • (d) Eurocurrency Borrowings :

      (1) Subject to the terms and conditions set forth herein, the Lenders severally agree to make Eurocurrency Loans, from time to time, to the Borrower as provided in Section 1.2(d)(2) , on the applicable Banking Day requested by the Borrower in accordance with the terms hereof, in an aggregate principal amount that when added to the principal outstanding of all other outstanding Revolving Credit Loans made by such Lender, not to exceed at any time outstanding such Lender’s Commitment; provided however , that after giving effect to any Eurocurrency Loan, the total principal amount outstanding of all Eurocurrency Loans shall not exceed the Eurocurrency Loan Limit.

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• • • (2) For each borrowing in Eurocurrency and each continuation of a borrowing in Eurocurrency the Borrower shall provide to the Agent a Eurocurrency Borrowing Request which shall constitute the Borrower’s irrevocable notice to the Agent and shall be appropriately completed and signed by the chief financial officer or other senior officer of the Borrower. A Eurocurrency Borrowing Request may not be given by telephone. Each Eurocurrency Borrowing Request must be received by the Agent not later than 11:00 a.m. Boston time. Each borrowing of or continuation of Eurocurrency Loans shall be in a principal amount of €500,000 or 500,000 Sterling or a whole multiple of €250,000 or 250,000 Sterling in excess thereof. Each Eurocurrency Borrowing Request shall specify (i) whether the Borrower is requesting a Eurocurrency Loan, or a continuation of a Eurocurrency Loan, (ii) the requested date of the borrowing or continuation, as the case may be, (iii) the principal amount of Eurocurrency Loans to be borrowed or continued, (iv) the duration of the Eurocurrency Interest Period with respect thereto and (v) the Eurocurrency requested. If the Borrower fails to give a timely Eurocurrency Borrowing Request requesting a continuation, then the applicable Eurocurrency Loans shall not be continued and at the expiration of the applicable Eurocurrency Interest Period shall become Base Rate Loans. If the Borrower requests a borrowing of, or continuation of, Eurocurrency Loans in any such Eurocurrency Borrowing Request, but fails to specify a Eurocurrency Interest Period, it will be deemed to have specified a Eurocurrency Interest Period of one month. After giving effect to all Eurocurrency Loans and all continuations thereof, there shall not be more than three Eurocurrency Interest Periods in effect with request to Eurocurrency Loans.

      (3) The Borrower may, upon written notice ("Eurocurrency Notice of Prepayment") to the Agent, at any time or from time to time voluntarily prepay Eurocurrency Loans, in whole or in part, without premium or penalty, provided that (i) such notice must be received by the Agent not later than 11:00 a.m. Boston time and shall specify the date and the amount of such prepayment three Banking Days prior to any date of prepayment; and (ii) any prepayment shall be in a principal amount of €500,000 or 500,000 Sterling or a whole multiple of €250,000 or 250,000 Sterling in excess thereof or, if less, the entire principal amount thereof then outstanding; provided , further that that if a Eurocurrency Loan is prepaid on any day other than the last day of the Eurocurrency Interest Period applicable thereto, the Borrower shall also pay the Eurocurrency Premium together with all other amounts due therefor under Section 2. If any such Eurocurrency Notice of Prepayment is given, the amount specified in such Eurocurrency Notice of Prepayment shall be due and payable on the date specified therein, together with accrued interest to such date on the amount prepaid and the other amounts required to be paid hereunder at such time in connection therewith.

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(d) Section 1.4 Interest; Applicable Margins is hereby deleted in its entirety and the following is inserted in lieu thereof:

• 1.4 Interest; Applicable Margins .

(a) The Revolving Credit Loans shall bear interest (computed on the basis of the actual number of days elapsed over a 360-day year) on the unpaid principal amount thereof until paid in full at the rate or rates per annum determined as follows:

• • • (i) The per annum rate for any portion of the outstanding principal balance of the Revolving Credit Notes which is not then subject to a LIBOR Option and which is not a Eurocurrency Loan shall be equal to the Applicable Base Rate Margin (as hereinafter defined in subsection 1.4(c)) plus the Base Rate;

      (ii) The per annum rate for any LIBOR Portion shall be equal to the Applicable LIBOR Margin (as hereinafter defined in subsection 1.4(c)) plus the LIBOR Rate; and

      (iii) The per annum rate for any Eurocurrency Loan shall be equal to the Applicable Eurocurrency Margin (as hereinafter defined in subsection 1.4(c)) plus the Eurocurrency Rate.

(b) Interest on any portion of the Revolving Credit Notes (i) accruing based upon the Base Rate shall be payable monthly in arrears on the first day of each month, commencing on the first such date next succeeding the date of issuance of the Revolving Credit Notes, (ii) accruing based upon the LIBOR Rate shall be payable on the earlier to occur of (x) the last day of the LIBOR Period applicable to such LIBOR Portion or (y) the 90th day of such LIBOR Period, and at maturity (whether by acceleration or otherwise) and (iii) accruing based upon the Eurocurrency Rate shall be payable on the earlier to occur of (x) the last day of the Eurocurrency Interest Period applicable to such Eurocurrency Loan or (y) the 90 ^th day of such Eurocurrency Interest Period, and at maturity (whether by acceleration or otherwise). Each change in the rate of interest payable on any portion of the outstanding principal balance of the Revolving Credit Notes which is not then subject to a LIBOR Option and which is not a Eurocurrency Loan shall take effect simultaneously with the corresponding change in the Base Rate. Notwithstanding anything contained herein or in any other Loan Document to the contrary, in no event shall the amount paid or agreed to be paid by the Borrower as interest on the Revolving Credit Loans exceed the highest lawful rate permissible under any law applicable thereto.

(c) Applicable Margin . For the purpose of this subsection 1.4, the " Applicable Margin " shall be determined as follows:

• • • (i) subject to the provisions of subparagraph (iii) hereof, from and after each Interest Adjustment Date until the next Interest Adjustment Date, the Applicable Margin for Base Rate Revolving Credit Loans (the " Applicable Base Rate Margin "), for Revolving Credit Loans subject to a LIBOR Option (the " Applicable LIBOR Margin ") and for Eurocurrency Loans (the " Applicable Eurocurrency Margin ") shall be the respective amounts set forth in the following table opposite the

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• • • applicable ratio of outstanding Total Funded Debt to Adjusted EBITDA:

• • • (ii) As used herein, the term " Interest Adjustment Date " shall mean (A) the first day of the first month after the date on which each of the quarterly compliance certificates (together with quarterly unaudited financial statements for such quarter) required to be delivered under subsection 5.1 (the " Required Financial Statements ") with respect to the then most recently ended quarter were due, if the foregoing table indicates an upward adjustment of the Applicable Margin, or (B) the later of such date or the first day of the first month after the date that all of the Required Financial Statements for such quarter shall have been received by the Agent, if the foregoing table indicates a downward adjustment of the Applicable Margin.

      (iii) The determination of the Applicable Margin hereunder as of any Interest Adjustment Date shall be based on unaudited quarterly financial statements and compliance certificates as provided above, provided, that in the event of any discrepancy between computations based upon any compliance certificates and the related audited financial statements furnished pursuant to subsection 5.1 (the " Audited Financial Statements ") the computation based upon the Audited Financial Statements shall govern (retroactive to the most recent Interest Adjustment Date). In the event of a retroactive correction in the determination of the Applicable Margin in favor of the Lenders, the amount of interest thereby overdue and payable by the Borrower shall be paid to the Agent for the account of each Lender in accordance with and proportionate to such Lender’s Commitment within five (5) Banking Days after the date of such retroactive correction. Notwithstanding any of the foregoing, upon any upward adjustment of the Applicable Margin, there shall be no subsequent downward adjustment of the Applicable Margin until the first day of the first month after the ratio of outstanding Total Funded Debt to Adjusted EBITDA would result in such downward adjustment as of the end of a subsequent fiscal quarter. Notwithstanding anything to the contrary set forth in this Agreement, no downward adjustment of the Applicable Margin

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• • • shall occur if, at the time such downward adjustment would otherwise be made, there shall exist any Event of Default, provided that such downward adjustment shall be made on the first day of the first month after the date on which any Event of Default preventing such downward adjustment shall have been cured in accordance with Section 12, assuming that no other Event of Default exists at the time of such downward adjustment.

(e) Section 1.5 Fees (a)  Unused Line Fee is hereby amended by adding the following as a last sentence to such section:

• • • "For purposes of such calculation, all Eurocurrency Loans shall be calculated in their Dollar Equivalent"

(f) Section 2 LIBOR Provisions is hereby deleted in its entirety and the following is inserted in lieu thereof:

Section 2. LIBOR Provisions; Eurocurrency Provisions .

2.1    (a) LIBOR Option . Subject to the provisions of this Section 2, the Borrower shall have the right to have the interest on all or any portion of the principal amount of the Revolving Credit Loans based on a LIBOR Rate.

(b) Eurocurrency . All Eurocurrency Loans shall bear interest based on the Eurocurrency Rate.

2.2 Certain Definitions . As used herein, the following terms have the following respective meanings:

• " Banking Day ": (i) when used with respect to the LIBOR Option or a Eurocurrency Loan, a day on which dealings may be effected in deposits of US dollars in the London interbank foreign currency deposits market or the purchase of Eurocurrency in the applicable Eurocurrency market and on which banks may conduct business in London, England and Boston, Massachusetts, and (ii) when used with respect to the other provisions of this Agreement, any day excluding Saturday and Sunday and excluding any other day which shall be in Boston, Massachusetts, a legal holiday or a day on which banking institutions are authorized by law to close.

  " Eurocurrency Premium ": with respect to the prepayment of any Eurocurrency Loan prior to the end of the Eurocurrency Interest Period applicable thereto, an amount equal to the product of (i) the excess, if any, of the original Eurocurrency Rate on the amount so prepaid over the Eurocurrency Rate of interest on Eurocurrency deposits, for the applicable Eurocurrency, in effect on the date of such prepayment and having a maturity date approximating the last Banking Day of the applicable Eurocurrency Interest Period, multiplied by (ii) the principal amount so prepaid, multiplied by (iii) a fraction, the numerator of which is the number of days remaining in the related Eurocurrency Interest Period and the denominator of which is 360. If the result of clause (i) is less than or equal to zero, there shall be no Eurocurrency Premium.

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• " Eurocurrency Base Rate ": for any Eurocurrency Interest Period with respect to any Eurocurrency Loan:

  (a) the rate per annum equal to the rate determined by the Agent to be the offered rate that appears on page 3750 of the Telerate screen (or any successor thereto) (or such other page of the Telerate as is customary for the Euro or Sterling) that displays an average British Bankers Association Interest Settlement Rate for deposits in Euro (for delivery on the first day of such Interest Period) if a Euro denominated loan and for deposits in Sterling (for delivery on the first day of such Interest Period) if a Sterling denominated loan with a term equivalent to such Interest Period, determined as of approximately 11:00 a.m., London time, two (2) Banking Days prior to the first day of such Eurocurrency Interest Period for a Euro denominated Loan and on the first day of such Eurocurrency Interest Period if a Sterling denominated Loan, or

  (b) if the rate referenced in the preceding clause (a) does not appear on such page or service or such page or service shall not be available, the rate per annum equal to the rate determined by the Agent to be the offered rate on such other page or other service that displays an average British Bankers Association Interest Settlement Rate for deposits in Euro (for delivery on the first day of such Interest Period) if a Euro denominated loan and for deposits in Sterling (for delivery on the first day of such Interest Period) if a Sterling denominated loan with a term equivalent to such Eurocurrency Interest Period, determined as of approximately 11:00 a.m., London time, two (2) Banking Days prior to the first day of such Eurocurrency Interest Period for a Euro denominated loan and on the first day of such Eurocurrency Interest Period if a Sterling denominated loan, or

  (c) if the rates referenced in the preceding clauses (a) and (b) are not available, the rate per annum determined by the Agent as the rate of interest at which deposits in Euro or Sterling, as the case may be, for delivery on the first day of such Eurocurrency Interest Period in the same day funds in the approximate amount of the Eurocurrency Loan being made, continued or converted by the Agent and with a term equivalent to such Eurocurrency Interest Period that would be offered to the Agent for the applicable Eurocurrency in the London interbank Eurocurrency market at its request at approximately 11:00 a.m., London time, two (2) Banking Days prior to such Eurocurrency Interest Period for a Euro denominated loan and on the first day of such Interest Period if a Sterling denominated loan.

  " Eurocurrency Rate ": for any Eurocurrency Interest Period with respect to any Eurocurrency Loan, a rate per annum determined by the Agent pursuant to the following formula:

• The determination of the Eurocurrency Rate by the Agent shall be conclusive in the absence of manifest error.

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• " Eurocurrency Reserve Percentage ": for any day during any Eurocurrency Interest Period, the reserve percentage (expressed as a decimal, carried out to five decimal places) in effect on such day, whether or not applicable to any Lender, under regulations issued from time to time by the FRB (or any other Governmental Authority having jurisdiction with respect thereto) for determining the maximum reserve requirement (including any emergency, supplemental or other marginal reserve requirement) with respect to eurocurrency funding (currently referred to as "Eurocurrency liabilities"). The Eurocurrency Rate for each outstanding Eurocurrency Loan shall each be adjusted automatically as of the effective date of any change in the Eurocurrency Reserve Percentage. The determination of the Eurocurrency Reserve Percentage by the Agent shall be conclusive in the absence of manifest error.

  " Eurocurrency Interest Period ": means as to each Eurocurrency Loan the period commencing on the date such Eurocurrency Loan is disbursed or converted to or continued as a Eurocurrency Loan, and ending on the date 30, 60 or 90 days thereafter, as selected by the Borrower in its Eurocurrency Borrowing Request, provided that:

  • • (i) any Eurocurrency Interest Period that would otherwise end on a day that is not a Banking Day shall be extended to the next succeeding Banking Day unless, in the case of a Eurocurrency Loan such Banking Day falls in another calendar month, in which case such Eurocurrency Interest Period shall end on the next preceding Banking Day;

      (ii) any Eurocurrency Interest Period pertaining to a Eurocurrency Loan that begins on the last Banking Day of a calendar month (or on a day for which there is no numerically corresponding day in the calendar month at the end of such Eurocurrency Interest Period) shall end on the last Banking Day of the calendar month at the end of such Eurocurrency Interest Period; and

      (iii) no Eurocurrency Interest Period shall extend beyond the Maturity Date.

  " FRB " means the Board of Governors of the Federal Reserve System of the United States.

  " Legal Requirement" : any requirement imposed upon the Agent or any Lender by any law of the United States of America or the United Kingdom or by any regulation, order, interpretation, ruling or official directive (whether or not having the force of law) of the Board, the Bank of England or any other board, central bank or governmental or administrative agency, institution or authority of the United States of America, the United Kingdom or any political subdivision of either thereof.

  Lender Tax : in relation to any LIBOR Portion and any Eurocurrency Loan and the applicable LIBOR Rate or Eurocurrency Rate, any tax,