SOLEXA ANNOUNCES MAJOR SEQUENCING PROGRESS AND TARGETS WHOLE HUMAN GENOME

HAYWARD, Calif. and Cambridge, UK (October 18, 2005) – Solexa, Inc. (Nasdaq: SLXA) today announced that its scientists have sequenced a human bacterial artificial chromosome (BAC), an important milestone demonstrating that Solexa’s reversible-terminator chemistry and Clonal Single-Molecule Array™ technology can be applied to resequence human DNA. The results of this project, which were presented today during the GSAC 2005 Genomes, Medicine and the Environment Conference, demonstrate that Solexa’s platform can achieve the data quality, read length and coverage uniformity required for economical and rapid resequencing of human DNA. Solexa expects its instrument system to be the first to dramatically reduce the cost, while also increasing the speed, of DNA sequencing. In particular, Solexa expects to be the first to deliver whole human genome sequencing at $100,000 per genome.

“In setting out to sequence this human BAC, our goal was to prove that our technology platform can address the complexities of human DNA sequencing,” said Tony Smith, Ph.D., Solexa’s vice president and chief scientific officer. “These results have important implications as they demonstrate that we can produce data of the necessary quality, and suggest we will be able to achieve the necessary scale, to resequence whole human genomes at or below $100,000 per sample.“

Solexa sequenced a BAC which contains 162,000 base pairs of human DNA from the HLA region. Using 25 base pair reads, Solexa scientists were able to uniquely align 90% of the BAC back to its own reference sequence. Additionally, Solexa scientists were able to:

• Achieve >99.99% consensus accuracy in alignment against the reference sequence;
• Correctly identify and call 100% of 153 polymorphisms in the sequenceable regions;
• Successfully sequence 99% of homopolymers (514 of 521) in the sequenceable regions, including repeats of up to 31 base pairs;
• Successfully resequence all dinucleotide repeats in the BAC;
• Attain relatively uniform sequencing coverage with minimal correlation to base composition; and
• Establish the absence of systematic sequence context-related errors.

While this work was completed using an early laboratory prototype instrument, Solexa anticipates releasing results of sequencing from its new laser-based instruments as they become available.

“We have developed our system with a focus on human samples and have formulated our work plan to sequence genomic samples that can be compared with independently published data, as this demonstrates proof-of-concept with our system,” said John West, Solexa’s chief executive officer. “Our sequencing strategy calls for sequencing progressively larger and more complex portions of the human genome in order to further validate the unique capabilities of our system in enabling rapid and economical whole genome resequencing. We have already obtained human whole genome DNA samples and are readying them for analysis using proprietary methods in order to meet these milestones.”

About Solexa

Solexa, Inc. is developing and preparing to commercialize a new genetic analysis instrument system which will be used to perform a range of analyses including whole genome resequencing, gene expression analysis and micro-RNA analysis. Solexa expects its first-generation technology to generate over a billion bases of DNA sequence per run and to enable whole genome resequencing below $100,000 per sample, making it the first platform to reach this important milestone. Solexa's longer-term goal is to reduce the cost of human re-sequencing to a few thousand dollars for use in a wide range of applications from basic research through clinical diagnostics. The Company expects to introduce its first instrument system by the end of 2005. For further information, please visit www.solexa.com .

This press release contains "forward-looking" statements, including statements related to the current views of Solexa management as to future products, product development including the commercial introduction of the Company’s novel genetic analysis technology, the expansion and success of Solexa's commercial application of its genomics technologies and the future financial performance of Solexa. Any statements contained in this press release that are not statements of historical fact may be deemed to be forward-looking statements. Words such as "believes," "anticipates," "plans," "predicts," "expects," "envisions," "hopes," "estimates," "intends," "will," "continue," "may," "potential," "should," "confident," "could" and similar expressions are intended to identify forward-looking statements. There can be no assurance that such expectations of any of the forward-looking statements will prove to be correct, and actual results could differ materially from those projected or assumed in the forward-looking statements. There are a number of important factors that could cause the results of Solexa to differ materially from those indicated by these forward-looking statements including, among others, risks detailed from time to time in the Company's SEC reports, including its Annual Report on Form 10-K for the year ended December 31, 2004 and its Form 10-Q for the quarter ended June 30, 2005. Solexa does not undertake any obligation to update forward-looking statements.

###

For more information, please contact: