Thirty-six subjects with osteoarthritis of the knee, the hip, and/or the spine were enrolled in a randomized double-blind study. Patients received a daily oral dose of 1,200 mg of S-adenosylmethionine (SAMe) or 1,200 mg of ibuprofen for four weeks. Morning stiffness, pain at rest, pain on motion, crepitus, swelling, and limitation of motion of the affected joints were assessed before and after treatment. The total score obtained by the evaluation of all the individual clinical parameters improved to the same extent in patients treated with SAMe or ibuprofen. Both treatments were well tolerated and no patient from either group withdrew from the study.