Osteoarthritis (OA)is a degenerative joint disease caused by gradual loss of cartilage. Telmisartan is an Angiotensin II receptor antagonist,and act as a partial agonist on the nuclear peroxisome proliferator-activated receptor-gamma (PPAR-γ),that has been reported to exert anti-inflammatory effects. This study was designed to evaluate the potential anti-inflammatory effect oftelmisartan in patients with knee OA.42 patients with painful knee OA were allocated into 2 groups,group (1): patients treated with naproxen tablets (500 mg/12 hr),telmisartan tablets (40 mg/day) and omeprazole (20 mg/day) for 3 months,while group (2): patients treated with naproxen tablets (500 mg/12hr) and omeprazole (20 mg/day) for 3 months. The serum levels of IL-1β,high-sensitivity C-reactive protein (hs-CRP),TNF-α anderythrocyte sedimentation rate (ESR) were measured before and after 3 months of treatment.Telmisartan when used in combination with naproxen resulted in significant decrease in serum levels of IL-1β and hs-CRP,higher than that produced by naproxen when used alone. The mean TNF-α level and ESR was decreased non-significantly in both study groups. Administration of telmisartan as an adjuvant therapy to naproxen in knee OA patients produced a significant decrease in the serum levels of IL-1β and hs-CRP,though no clear effect on TNF-α and ESR was noticed after 3 months treatment. Accordingly,many promising preventive strategies emerged from the available results since telmisartan relatively reduce the inflammatory burden in OA patients.