Twenty-one patients between the ages of 68 and 89 years with osteoarthrosis of hips and/or knee joints wre studied. One group was treated with fenoprofen 300 mg t.d.s. for 5 days, and the other group with 600 mg t.d.s. for 5 days. No therapeutic advantage was found with the higher dose, and the side-effects were minimal on either dosage. Treatment of elderly patients with the smaller dose is recommended.