Osteoarthritis is a leading chronic disease in older adults characterized by degeneration of articular cartilage of the joints in hands, spine, knees and hips. Tissue injury and pain are caused by conversion of arachidonic acid in joints to such inflammatory compounds as PGE2 and LTB4 by cyclooxygenase (COX) and 5-lipoxygenase (5-LO) enzymes. Conventional non-steroidal anti-inflammatory drugs (NSAIDs) inhibit COX-1 and COX-2 isoenzymes, but have a marginal or no effect on 5-LO. A "dual inhibitor" of COX and 5-LO offers potential clinical benefits beyond existing nonsteroidal anti-inflammatory drugs (NSAIDs). NSAIDs provide symptomatic relief, but they can be associated with significant side effects that include gastrointestinal bleeding, venous thrombosis, and nephrotoxicity. Thus, novel alternative therapies with increased safety and efficacy are desirable. Natural substances might be a useful alternative. Flavocoxid is a botanical extract or medical food ingredient derived from two plants, Scutellaria baicalensis and Acacia catechu that inhibit COX-I and COX-2 as well as 5-LO. Medical foods are formulated to meet therapeutic dietary needs of specific patient populations using Generally Recognized As Safe (GRAS) ingredients under a physician's supervision. Safety testing of flavocoxid in animals has revealed no significant toxicity. The proposed study is a randomized, double blind, placebo-controlled trial to evaluate the safety and preliminary efficacy of flavocoxid. Seventy patients with knee OA, who meet the eligibility criteria for the study and consent to participate, will be assigned to one of two groups (flavocoxid vs. identical placebo) and will be evaluated for 12 weeks. Study assessments scheduled every 2 weeks will include safety monitoring, clinical laboratory tests, quality of life and measures of efficacy as determined by the Western Ontario and McMaster (WOMAC) osteoarthritis index, and patient/physician global disease ratings. This innovative compound has commercial potential with its expected efficacy comparable to or exceeding the currently marketed COX inhibitors but with fewer side effects and at a significantly lower cost.