808 patients, combined from two trials, with knee osteoarthritis were randomized to receive either celecoxib 200mg daily, rofecoxib 12.5mg daily, or placebo. Patients were assessed over a 6-week period of treatment on a Patient Global Assessment of Response to Therapy (PGART), the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) Pain and Physical Function subscales, and the incidence of adverse events. Both celecoxib and rofecoxib were associated with significantly better results regarding PGART and WOMAC score compared to placebo. No significant differences were noted in the incidence of adverse events. Readers should note that since the time of publication, rofecoxib has been withdrawn from the market due to concerns regarding cardiovascular safety.