Illumina Announces SentrixTM BeadChip Platform

June 12, 2003

New Microarray Substrate Complements Sentrix Fiber-Based Array Matrix

SAN DIEGO, CALIFORNIA, June 12, 2003 -- Illumina, Inc. (Nasdaq: ILMN) announced today that it has developed and is manufacturing a novel microarray substrate that will significantly expand market opportunities for its BeadArrayTM technology and provide increased experimental flexibility for life science researchers.

SentrixTM BeadChips are manufactured using highly flexible MEMS (microelectronic mechanical systems) technology, allowing creation of any number of microfabricated wells clustered into discrete regions on a substrate. These regions are populated with beads, and the resulting BeadChip is processed using the same methods perfected for the fiber-based Sentrix Array Matrix. Each region can interrogate a separate sample and can be configured in different sizes and densities -- standard and custom -- depending on researcher requirements.

Initial BeadChip formats will be sized like standard slide arrays. Additional sizes can be added to the line to accommodate custom configurations. The BeadChip format will supplement the Sentrix fiber-based array matrices now being used by Illumina's production genotyping services operation and by the Company's BeadLab customers. Collectively, the expanded line of Sentrix arrays delivers even greater power to the multi-sample Array of Arrays® approach that Illumina invented and introduced to the high-throughput genomics market.

Sentrix BeadChips will support the same applications as the Company's fiber array matrices, including SNP genotyping and RNA profiling. Sets of beads with immobilized probe sequences can be deployed interchangeably on both substrates.

Jay Flatley, Illumina President and CEO, stated "We have invested heavily in the development of this complementary new platform and we're excited to bring the expanded technology into the marketplace. The Sentrix platform addition will give researchers the flexibility to use our technology over a wider range of samples and probes, and enable individual projects to be conducted on a smaller scale than that required in production-scale facilities now using the Array Matrix. We expect our first BeadChip-based products to be launched over the next few quarters."

Illumina (www.illumina.com) is developing next-generation tools that permit large-scale analysis of genetic variation and function. The Company's proprietary BeadArray® technology provides the throughput, cost effectiveness and flexibility to enable researchers in the life sciences and pharmaceutical industries to perform the billions of tests necessary to extract medically valuable information from advances in genomics and proteomics. This information will help pave the way to personalized medicine.

"Safe Harbor" Statement under the Private Securities Litigation Reform Act of 1995: this release may contain forward-looking statements that involve risks and uncertainties. Among the important factors which could cause actual results to differ materially from those in the forward-looking statements are Illumina's ability to manufacture Sentrix BeadChips in a robust and cost-effective manner, to fully develop its BeadArray and Oligator technologies, the Company's ability to successfully build international sales and support organizations to install and service its laboratory facilities at customer locations, the Company's ability to develop and deploy new applications for its platform technology, and other factors detailed in the Company's filings with the Securities and Exchange Commission including its recent filings on Forms 10-K and 10-Q or in information disclosed in public conference calls, the date and time of which are released beforehand. Illumina disclaims any intent or obligation to update these forward-looking statements beyond the date of this release.

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