Helicos BioSciences Names Louise Mawhinney Vice President & Chief Financial Officer

Helicos BioSciences Corporation

Helicos BioSciences Names Louise Mawhinney Vice President & Chief Financial Officer

October 12, 2006

CAMBRIDGE, Mass.— October 12, 2006 --Helicos BioSciences, a pioneer in high-speed, high-sensitivity sequencing, announced today that it has named longtime financial executive Louise Mawhinney as Vice President and Chief Financial Officer.

Stanley N. Lapidus, President and CEO of Helicos, said, “We are pleased to have Louise join our executive team. Her operational expertise and deep experience with the financial markets is a great addition to my staff and provides a crucial skill set required for our continued evolution as a company.”

“I am excited to join Helicos. The management team and the science are both very impressive,” said Mawhinney. “Helicos is evolving rapidly and I am looking forward to contributing to its future success.”

Mawhinney joins Helicos with over 10 years experience as a Chief Financial Officer, most recently at ArQule Inc., a biotechnology company engaged in the research and development of cancer therapeutics. She was instrumental in securing funding for ArQule that included an equity offering.

From 2000 – 2003, Mawhinney was Chief Financial Officer and a founding member of Cleanwise Inc., a venture funded “dot.com” that she helped grow from start-up to multi-million dollars in revenue. Mawhinney had previously served as Chief Financial Officer at The Butcher Company, where she played a key role in two successful acquisitions, and as group controller at Lifetime Corporation. Prior to that, she was at KPMG in Boston.

About tSMS™

tSMS™ is a technique that enables researchers to rapidly and accurately sequence individual molecules of DNA and RNA. This allows direct interrogation of the single molecule as opposed to an amplified population of molecules. tSMS™ holds enormous potential for elucidating the gamut of genetic aberrations in oncology, through the ability to serve as a universal detection system across a wide variety of applications for both DNA and RNA.

An example of some of the applications tSMS™ will enable are whole tumor resequencing, quantitative transcriptional profiling, genome wide methylation studies, and candidate gene resequencing.

The advantages of tSMS™ over amplified molecule sequencing include: no PCR bias, no errors introduced by amplification, and no dephasing issues commonly present in amplified molecule sequencing. In addition, tSMS™ promises the highest possible throughput and enables reagent cost savings on the order of 1,000 times less than Sanger sequencing.

About Helicos BioSciences

Helicos BioSciences Corporation began operations in February 2004, and has raised $67 million from a top-tier investment consortium to date. Helicos is developing instruments and reagents for the high-speed sequencing of DNA and RNA with the highest possible sensitivity. The Helicos technology, based on pioneering research of Dr. Stephen Quake of Stanford University, is covered by a broad portfolio of granted and filed patents. The company commenced early-access collaborations in 2006 to generate ground breaking scientific publications and start creating revenue, while planning to launch its first commercial systems in 2007.