Proprietary Information and Inventions Agreement

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CERTAIN CONFIDENTIAL INFORMATION CONTAINED IN THIS DOCUMENT, MARKED BY BRACKETS,

HAS BEEN OMITTED PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT PURSUANT TO

RULE 24B-2 UNDER THE SECURITIES EXCHANGE ACT OF 1934, AS AMENDED. THE OMITTED

MATERIAL HAS BEEN FILED SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION.

[ILLUMINA LOGO]

                                                                   Exhibit 10.31

February 15, 2005

Alan Kersey

Re:  Illumina, Inc.

Dear Alan:

It gives me great pleasure to set forth the principal terms for you to join

Illumina, Inc. (the "Company").

Position:                 VP & Site General Manager

Responsibilities:         VP/Site General Manager is a position of scientific

                          and technical leadership for the CyVera subsidiary

                          upon the merger with Illumina, Inc. Principal

                          responsibilities will include:

                          o     Direct leadership of the CyVera subsidiary.

                          o     Development of strategies for the CyVera

                                business.

                          o     Participation with the senior management team to

                                define future products.

                          o     Achievement of the CyVera business and

                                financial goals.

                          o     Other such matters that may be determined by the

                                management team.

                          As a Company employee you will be expected to abide by

                          all the Company policies and procedures and sign and