January 25, 2012

Dear Colleagues,

We just recently announced an offer to acquire Illumina, Inc., a leading developer of technology used to study genetic variation and function. Illumina’s portfolio includes innovative and market-leading tools for DNA and RNA analysis that enable rapid advances in basic and disease research and diagnostics. This acquisition will strengthen Roche’s position in Sequencing and Microarrays and Roche’s current portfolio in the areas of genetics and genomics research and diagnostics.

The ongoing evolution of technology is transforming sequencing into an increasingly powerful, usable and affordable tool that may enable it to deliver applications outside of the research area. We are convinced that Roche and Illumina’s combined capabilities and global reach will help accelerate the transition of sequencing into clinical and routine diagnostics providing additional meaningful information for the diagnosis and treatment of patients. Together, Roche and Illumina’s technologies will enable Roche to provide researchers in many different fields a total solution for their needs. Roche’s large customer network, extensive diagnostics experience and global presence will help accelerate the transition of DNA sequencing into clinical and routine diagnostics.

We intend to continue the Illumina legacy within our Diagnostics Division maintaining the Illumina brand. We also intend to combine our existing Applied Science business with Illumina and move the business area’s headquarters to San Diego, California. We plan to maintain operations in Penzberg, Germany, the current headquarters of our Applied Science business.

It is our preferred approach to reach an agreement with Illumina’s Board of Directors to complete this transaction. We made multiple efforts to engage in constructive dialogue with Illumina in order to reach a negotiated transaction, but have not been successful. Following the announcement of our offer today, we will promptly begin a tender offer for all outstanding shares of Illumina. We still remain willing to discuss a negotiated transaction with Illumina.

Attached is the press release we issued this morning, which provides additional details on our offer. We will also send out an invitation for a global employee webcast to all of our colleagues in Diagnostics shortly. We will keep you apprised of any significant further developments in this process.

Best regards,

Severin Schwan, CEO of Roche Group

Daniel O’Day, COO, Diagnostics

CAUTIONARY STATEMENT REGARDING FORWARD-LOOKING STATEMENTS

THESE MATERIALS CONTAIN CERTAIN FORWARD-LOOKING STATEMENTS. THESE FORWARD-LOOKING STATEMENTS MAY BE IDENTIFIED BY WORDS SUCH AS “BELIEVES”, “EXPECTS”, “ANTICIPATES”, “PROJECTS”, “INTENDS”, “SHOULD”, “SEEKS”, “ESTIMATES”, “FUTURE” OR SIMILAR EXPRESSIONS OR BY DISCUSSION OF, AMONG OTHER THINGS, STRATEGY, GOALS, PLANS OR INTENTIONS. VARIOUS FACTORS MAY CAUSE ACTUAL RESULTS TO DIFFER MATERIALLY IN THE FUTURE FROM THOSE REFLECTED IN FORWARD-LOOKING STATEMENTS CONTAINED IN THIS DOCUMENT, AMONG OTHERS: (1) ECONOMIC AND CURRENCY CONDITIONS; (2) COMPETITIVE AND TECHNOLOGICAL FACTORS; AND (3) RISKS AND UNCERTAINTIES RELATING TO THE PROPOSED TRANSACTION.

ADDITIONAL INFORMATION AND WHERE TO FIND IT

THESE MATERIALS ARE FOR INFORMATIONAL PURPOSES ONLY AND DO NOT CONSTITUTE AN OFFER TO PURCHASE OR A SOLICITATION OF AN OFFER TO SELL ILLUMINA COMMON STOCK. THE SOLICITATION AND OFFER TO BUY ILLUMINA COMMON STOCK WILL ONLY BE MADE PURSUANT TO AN OFFER TO PURCHASE AND RELATED MATERIALS. INVESTORS AND SECURITY HOLDERS ARE URGED TO READ THESE MATERIALS CAREFULLY WHEN THEY BECOME AVAILABLE SINCE THEY WILL CONTAIN IMPORTANT INFORMATION, INCLUDING THE TERMS AND CONDITIONS OF THE OFFER. THE OFFER TO PURCHASE AND RELATED MATERIALS WILL BE FILED BY ROCHE WITH THE SECURITIES AND EXCHANGE COMMISSION (SEC), AND INVESTORS AND SECURITY HOLDERS MAY OBTAIN A FREE COPY OF THESE MATERIALS (WHEN AVAILABLE) AND OTHER DOCUMENTS FILED BY ROCHE WITH THE SEC AT THE WEBSITE MAINTAINED BY THE SEC AT WWW.SEC.GOV. THE OFFER TO PURCHASE AND RELATED MATERIALS MAY ALSO BE OBTAINED (WHEN AVAILABLE) FOR FREE BY CONTACTING THE INFORMATION AGENT FOR THE TENDER OFFER, MACKENZIE PARTNERS, AT (212) 929-5500 OR (800) 322-2885 (TOLL-FREE).

ROCHE WILL BE FILING A PROXY STATEMENT ON SCHEDULE 14A AND OTHER RELEVANT DOCUMENTS WITH THE SEC IN CONNECTION WITH ITS SOLICITATION OF PROXIES FOR THE 2012 ANNUAL MEETING OF ILLUMINA (THE “PROXY STATEMENT"). PROMPTLY AFTER FILING A DEFINITIVE PROXY STATEMENT WITH THE SEC, ROCHE WILL MAIL THE PROXY STATEMENT AND A PROXY CARD TO EACH ILLUMINA STOCKHOLDER ENTITLED TO VOTE AT THE 2012 ANNUAL MEETING. INVESTORS AND SECURITY HOLDERS ARE URGED TO READ THE PROXY STATEMENT CAREFULLY AND IN ITS ENTIRETY WHEN IT BECOMES AVAILABLE AND ANY OTHER RELEVANT DOCUMENTS FILED WITH THE SEC BECAUSE THEY WILL CONTAIN IMPORTANT INFORMATION. INVESTORS AND SECURITY HOLDERS MAY OBTAIN A FREE COPY OF THESE MATERIALS (WHEN AVAILABLE) AND OTHER DOCUMENTS FILED BY ROCHE WITH THE SEC AT THE WEBSITE MAINTAINED BY THE SEC AT WWW.SEC.GOV. THE PROXY STATEMENT AND RELATED MATERIALS MAY ALSO BE OBTAINED (WHEN AVAILABLE) FOR FREE BY CONTACTING THE INFORMATION AGENT FOR THE TENDER OFFER, MACKENZIE PARTNERS, AT (212) 929-5500 OR (800) 322-2885 (TOLL-FREE).

ROCHE HOLDING LTD, CKH ACQUISITION CORPORATION AND THE INDIVIDUALS NOMINATED BY CKH ACQUISITION CORPORATION FOR ELECTION TO ILLUMINA’S BOARD OF DIRECTORS (THE “ROCHE NOMINEES") MAY BE DEEMED TO BE PARTICIPANTS IN THE SOLICITATION OF PROXIES FROM ILLUMINA STOCKHOLDERS FOR USE AT THE 2012 ANNUAL MEETING OF STOCKHOLDERS, OR AT ANY ADJOURNMENT OR POSTPONEMENT THEREOF. THE DIRECTORS AND EXECUTIVE OFFICERS OF ROCHE HOLDING LTD AND CKH ACQUISITION CORPORATION WHO MAY BE PARTICIPANTS IN THE SOLICITATION OF PROXIES HAVE NOT BEEN DETERMINED AS OF THE DATE OF THESE MATERIALS. NO ADDITIONAL COMPENSATION WILL BE PAID TO SUCH DIRECTORS AND EXECUTIVE OFFICERS FOR SUCH SERVICES. INVESTORS AND SECURITY HOLDERS CAN OBTAIN ADDITIONAL INFORMATION REGARDING THE DIRECT AND INDIRECT INTERESTS OF THE ROCHE NOMINEES AND OTHER PARTICIPANTS BY READING THE DEFINITIVE PROXY STATEMENT WHEN IT BECOMES AVAILABLE.

Transaction Valuation*		Amount of Filing Fee*
N/A		N/A

*	A filing fee is not required in connection with this filing as it relates solely to preliminary communications made before the commencement of a tender offer.

Amount Previously Paid:	Not applicable.		Filing Party:	Not applicable.
Form or Registration No.:	Not applicable.		Date Filed:	Not applicable.