Prometheus Highlights Record Performance in 2008

San Diego, March 24, 2009 – Prometheus Laboratories Inc., a specialty pharmaceutical and diagnostic company, today highlighted its financial results and product development progress for the year ended December 31, 2008.

"Prometheus had another record year in 2008, our 12th consecutive year of sales growth," said Joseph M. Limber, President and Chief Executive Officer of Prometheus. "In addition, we made significant progress advancing a number of internal development programs, all of which we believe will help to strongly position us for future growth. We continue to pursue additional opportunities through product licensing or acquisition or through strategic mergers or acquisitions. We are also preparing to expand into additional commercially attractive therapeutic areas, including oncology, that are consistent with our unique business model of offering proprietary and complementary pharmaceutical and diagnostic products."

Financial Highlights

• Prometheus reported a 26% increase in net sales to $278.1 million for 2008, compared to $220.9 million in 2007. For the five-year period 2004 through 2008, the Company’s net sales have grown by a compounded annual growth rate (CAGR) of 32.7%.

• During this same five-year period, aggregate net sales of pharmaceutical products grew from $38.9 million to $196.0 million, representing a CAGR of 49.8%

• Aggregate net sales of diagnostic testing services grew from $50.7 million in 2004 to $82.1 million in 2008, a CAGR of 12.8%.

• The Company reported earnings before interest, taxes, depreciation and amortization (EBITDA) of $73.2 million and net income of $37.2 million in 2008.

• As of December 31, 2008, the Company had cash and cash equivalents of $96.7 million.

Product Development Highlights

• 2008 marked the launch of PROMETHEUS� IBS Diagnostic, the first blood test for irritable bowel syndrome (IBS). This novel test incorporates ten biomarkers, two of which are proprietary, along with a proprietary algorithm to help physicians clarify or validate other clinical findings. Without a blood-based test to complement a physician’s clinical findings, the diagnosis of IBS is typically made through a process of elimination. The Company recently received approval from the New York State Department of Health for PROMETHEUS IBS Diagnostic.

• In May 2008, Prometheus began a Phase 2 clinical trial to evaluate COLAL-PRED� (prednisolone metasulfobenzoate sodium) for the treatment of patients with ulcerative colitis. COLAL-PRED is a development-stage product based on a drug delivery technology designed to release an anti-inflammatory steroid in the colon to provide the efficacy of steroids while limiting their undesirable systemic side effects.

• Prometheus advanced the development of its proprietary oncology diagnostics platform in 2008. The Company’s oncology diagnostics will utilize circulating tumor cells (CTCs) isolated from whole blood and/or tissue samples to help guide the use of targeted therapies. Prometheus believes such diagnostics would be more convenient and less invasive than current practices. The Company is preparing an application for New York State approval.

About Prometheus
Prometheus Laboratories Inc. is a specialty pharmaceutical and diagnostic company committed to developing and commercializing novel pharmaceutical and diagnostic products to help physicians individualize patient care. Prometheus is currently focused on the detection, diagnosis and treatment of gastrointestinal diseases and disorders in the United States. Its strategy includes the marketing and delivery of pharmaceutical products complemented by proprietary, high-value diagnostic testing services. By integrating pharmaceutical products and diagnostic testing services, Prometheus believes it can address the full continuum of care, thereby providing physicians with a comprehensive solution to treat chronic diseases. Prometheus’ corporate offices are located in San Diego, California.

Contact
Pete De Spain
Director, Investor Relations
& Corporate Communications
Prometheus Laboratories Inc.
(858) 587-4117
pdespain @prometheuslabs.com