HAYWARD, Calif. and Cambridge, UK (October 18, 2006) – Solexa, Inc. (NASDAQ: SLXA) yesterday announced that its scientists, in collaboration with researchers at the Wellcome Trust Sanger Institute, have sequenced a human X-chromosome. The initial results from this project, which were presented yesterday at the Genomes, Medicine and the Environment Conference in Hilton Head, South Carolina, demonstrate that the Solexa Genome Analysis System is achieving the data quality, read length and coverage uniformity required for discovering and characterizing human sequence variation at the genome-wide level. Solexa expects to be the first to deliver whole human genome sequencing at $100,000 per genome.

“In sequencing a human X-chromosome to an average 16-fold depth, we are displaying for the first time the performance of our technology in sequencing at whole genome scale,” said Tony Smith, Ph.D., Solexa’s vice president and chief scientific officer. “We believe these results signify that researchers worldwide will be able to apply our technology to resequence whole human genomes at a fraction of the cost and time required by other platforms.”

Scientists at Solexa and the Sanger Institute sequenced purified human X-chromosome DNA from an anonymous female individual and aligned 2.6 gigabases (billion bases) of high quality data to the 155-megabase (million base) reference sequence. While the scientists intend to add more coverage to this draft sequence in preparation for data release, they were able in their analysis to date to:

• Achieve 16-fold average coverage, with at least 2-fold coverage across >99% of sequenceable bases;
• Achieve >99.99% coverage of all sequenceable exonic bases;
• Confirm 96% of a test set of previously ascertained dbSNP genotypes in this sample and obtain preliminary evidence for the remaining 4%;
• By full genome re-alignment, identify fragments from other chromosomes remaining in the sample as a result of the flow-sorting method used to purify the X-chromosome; these fragments were present at a frequency in line with expectations for this experimental technique (~10%);
• Demonstrate uniform sequencing coverage; and
• Demonstrate the absence of systematic sequence context-related artifacts.

In addition to announcing its draft sequence of a human X-chromosome, Solexa also presented data from digital gene expression, small RNA analysis, microbial resequencing and candidate region resequencing applications. The high quality and breadth of this applications data illustrate that the Solexa Genome Analysis can effectively address a range of important genetic analysis applications today.

“We are delighted with the landmark results of this collaboration with researchers at the Sanger Institute,” said John West, Solexa’s chief executive officer. “These initial results from sequencing a human X-chromosome using the Solexa Genome Analysis System validate our belief that Solexa’s groundbreaking technology will enable researchers to tackle larger-scale projects and to do so much more rapidly and economically than ever before. Further, these results serve as an important model for our ongoing internal efforts to sequence a human genome, which we expect to complete to draft level by the end of the year.”

Solexa intends to provide an update on its commercial activities, including its Early Access Program, with its third quarter earnings release.

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About Solexa

Solexa, Inc. is developing and commercializing the Solexa Genome Analysis System, which will be used to perform a range of analyses including whole genome resequencing, gene expression analysis and small RNA analysis. Solexa expects its first-generation instrument, the 1G Genome Analyzer, to generate over a billion bases of DNA sequence per run and to enable human 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. 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, the commercial introduction of the Company’s novel genetic analysis technology and the expansion and success of Solexa's commercial application of its genomics technologies. 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, 2005 and its Form 10-Q for the quarter ended June 30, 2006. Solexa does not undertake any obligation to update forward-looking statements.

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