SENIOR SECURED PROMISSORY NOTE

THE SECURITIES REPRESENTED BY THIS CERTIFICATE (THE “SECURITIES”) HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE “SECURITIES ACT”) OR ANY STATE SECURITIES LAWS AND MAY NOT BE SOLD, TRANSFERRED OR OTHERWISE DISPOSED OF UNLESS REGISTERED UNDER THE SECURITIES ACT AND UNDER APPLICABLE STATE SECURITIES LAWS OR IMPLANT SCIENCES CORPORATION SHALL HAVE RECEIVED AN OPINION OF COUNSEL THAT REGISTRATION OF SUCH SECURITIES UNDER THE SECURITIES ACT AND UNDER THE PROVISIONS OF APPLICABLE STATE SECURITIES LAWS IS NOT REQUIRED.

For value received, IMPLANT SCIENCES CORPORATION, a corporation organized under the laws of the Commonwealth of Massachusetts (the “ Maker ” or the “ Company ”), hereby promises to pay to the order of DMRJ GROUP, LLC, a Delaware limited liability company, with an address at 152 West 57 ^th Street, 4 ^th Floor, New York, NY 10019 (together with its successors, representatives, and assigns, the “ Holder ”), in accordance with the terms hereinafter provided, the principal amount of One Million Dollars ($1,000,000) hereunder, together with interest and all other obligations outstanding hereunder.

All payments under or pursuant to this Senior Secured Promissory Note (this “ Note ”) shall be made in United States Dollars in immediately available funds to the Holder at the address of the Holder first set forth above or at such other place as the Holder may designate from time to time in writing to the Maker or by wire transfer of funds to the Holder’s account, instructions for which are attached hereto as Exhibit A .  The outstanding principal balance of this Note plus all outstanding interest and all other amounts owing hereunder shall be due and payable on December 10, 2009 (the “ Maturity Date ”) or at such earlier time as provided in Section 1.3 below.

Section 1.1   Purchase Agreement .  This Note has been executed and delivered pursuant to the Note and Warrant Purchase Agreement, dated as of December 10, 2008 (as amended, modified, replaced or restated from time to time, the “Purchase Agreement”), by and between the Maker and the Holder (as an Investor) and is the Additional Note referenced in that certain First Amendment to Note and Warrant Purchase Agreement, dated as of the date hereof, by and between the Maker and the Holder (as an Investor).  Capitalized terms used and not otherwise defined herein shall have the meanings set forth for such terms in the Purchase Agreement.

Section 1.2   Interest.   The Maker will pay interest to the Holder, payable on the Maturity Date or at such earlier time as payment is made pursuant, at a rate equal to the lesser of two and one half percent (2.5%) per month (prorated for partial months) and the maximum applicable legal rate per annum, computed on the basis of a 360-day year of twelve (12) thirty-

Section 1.3   Payment of Principal; Prepayment .  The outstanding principal balance of this Note and all other amounts owing hereunder shall be due and payable upon the Maker receiving net proceeds of at least $3,000,000 from the issuance and sale, in one or more transactions, of its debt and/or equity.  Notwithstanding the foregoing, the principal balance hereunder and all other amounts may be payable in full at such earlier time upon acceleration of this Note in accordance with the terms hereof.  Any amount of principal repaid hereunder may not be reborrowed.  The Maker may prepay all or any portion of the principal amount of this Note in an amount equal to the sum of (i) 100% of the amount of the principal prepayment, and (ii) all outstanding interest and all other amounts due and owing hereunder, upon not less than three (3) Business Days prior written notice to the Holder, without other penalty or premium.  This Note is further subject to mandatory prepayment at the option of the Holder as set forth in Article 4 hereof.

Section 1.4   Security Documents .  The obligations of the Maker hereunder are secured by a continuing security interest in substantially all of the assets of the Maker pursuant to the terms of a Security Agreement by and between the Maker and the Holder and other collateral documents.

Section 1.5   Payment on Non-Business Days .  Whenever any payment to be made shall be due on a Saturday, Sunday or a public holiday under the laws of the State of New York, such payment shall be due on the next succeeding Business Day and such next succeeding day shall be included in the calculation of the amount of accrued interest payable on such date.

Section 1.6   Transfer.   This Note may be transferred or sold, and may also be pledged, hypothecated or otherwise granted as security, by the Holder; provided, however, that any transfer or sale of this Note must be in compliance with any applicable securities laws.

Section 1.7   Replacement.   Upon receipt of a duly executed, notarized and unsecured written statement from the Holder with respect to the loss, theft or destruction of this Note (or any replacement hereof) and a standard indemnity, or, in the case of a mutilation of this Note, upon surrender and cancellation of such Note, the Maker shall issue a new Note, of like tenor and amount, in lieu of such lost, stolen, destroyed or mutilated Note.

Section 1.8   Use of Proceeds .  The Maker shall use the proceeds of this Note as set forth in the Purchase Agreement.

Section 2.1   Events of Default .  The occurrence of any of the following events shall be an “ Event of Default ” under this Note:

(a)   any failure to make any payment of the principal amount, interest or any other monetary obligation under this Note, as and when the same shall be due and payable (whether on the Maturity Date or by acceleration or otherwise); or

(b)   the Maker shall fail to observe or perform any other condition, covenant or agreement contained in this Note and such failure continues for a period of ten (10) days after the earlier of (i) the date on which such failure first becomes known to any officer of the Maker or (ii) notice thereof is given to the Maker by Holder; or

(c)   the suspension from listing, without subsequent listing on any one of, or the failure of the Common Stock to be listed on at least one of the OTC Bulletin Board, the Nasdaq Capital Markets, the Nasdaq Global Market, the Nasdaq Global Select Market, The New York Stock Exchange, Inc. or the NYSE Alternext Exchange for a period of five (5) consecutive Trading Days, such a suspension to only constitute an Event of Default if the Holder provides the Maker written notification that it deems such suspension to be an Event of Default; or

(d)   the Maker shall default in the performance or observance of any undertaking, covenant, condition or agreement contained in Sections 3.5, 3.6, 3.12, 3.13, 3.15, 3.16, 3.19, 3.20, 3.22, 3.24, 3.30, and 3.31 of the Purchase Agreement;  or

(e)   the Maker shall default in the performance or observance of any undertaking, covenant, condition or agreement contained in the Purchase Agreement (other than Sections 3.5, 3.6, 3.12, 3.13, 3.15, 3.16, 3.19, 3.20, 3.22, 3.24, 3.30, and 3.31 of the Purchase Agreement) or any other Transaction Document and such failure continues for a period of ten (10) days after the earlier of (i) the date on which such failure first becomes known to any officer of the Maker or (ii) notice thereof is given to the Maker by Holder;  or

(f)   any representation or warranty made by the Maker herein or in the Purchase Agreement or any other Transaction Document shall prove to have been false or incorrect or breached in a material respect on the date as of which made; or

(g)    (A) a default in any payment of any amount or amounts of principal of or interest on any Indebtedness of the Maker (other than the Indebtedness hereunder), the aggregate principal amount of which Indebtedness is in excess of $50,000   or (B) a default in the observance or performance of any other agreement or condition relating to any Indebtedness or contained in any instrument or agreement evidencing, securing or relating thereto, or any other event shall occur or condition exist, the effect of which default or other event or condition is to cause, or to permit, after any applicable grace period, the holder or holders or beneficiary or

(h)   the Maker shall (i) apply for or consent to the appointment of, or the taking of possession by, a receiver, custodian, trustee or liquidator of itself or of all or a substantial part of its property or assets, (ii) make a general assignment for the benefit of its creditors, (iii) commence a voluntary case under the United States Bankruptcy Code (as now or hereafter in effect) or under the comparable laws of any jurisdiction (foreign or domestic), (iv) file a petition seeking to take advantage of any bankruptcy, insolvency, moratorium, reorganization or other similar law affecting the enforcement of creditors’ rights generally, (v) acquiesce in writing to any petition filed against it in an involuntary case under United States Bankruptcy Code (as now or hereafter in effect) or under the comparable laws of any jurisdiction (foreign or domestic), (vi) issue a notice of bankruptcy or winding down of its operations or issue a press release regarding same, or (vii) take any action under the laws of any jurisdiction (foreign or domestic) analogous to any of the foregoing; or

(i)   a proceeding or case shall be commenced in respect of the Maker, without its application or consent, in any court of competent jurisdiction, seeking (i) the liquidation, reorganization, moratorium, dissolution, winding up, or composition or readjustment of its debts, (ii) the appointment of a trustee, receiver, custodian, liquidator or the like of Maker or of all or any substantial part of Maker’s assets or (iii) similar relief in respect of it under any law providing for the relief of debtors, and such proceeding or case described in clause (i), (ii) or (iii) shall continue undismissed, or unstayed and in effect, for a period of thirty (30) days or any order for relief shall be entered in an involuntary case under United States Bankruptcy Code (as now or hereafter in effect) or under the comparable laws of any jurisdiction (foreign or domestic) against the Maker or action under the laws of any jurisdiction (foreign or domestic) analogous to any of the foregoing shall be taken with respect to the Maker and shall continue undismissed, or unstayed and in effect for a period of sixty (60) days; or

(j)   a judgment or judgments in the aggregate amount exceeding $50,000 is/are entered against the Maker and not dismissed or discharged within twenty (20) days following the entr