A controlled research has been carried out in 39 patients with osteoarthrosis in order to evaluate the efficacy of Indoprofen, a new analgesic-antiinflammatory compound. This product, a phenylpropionic acid derivative, was given by mouth at the dose of 600 mg daily for 7 days. For comparison a treatment with 900 mg daily of Ibuprofen for the same length of time was given to patients according to a double-blind cross-over experimental design. Significant decrease in overall pain intensity was observed together with significant improvement in motility. Indoprofen at the daily dose of 600 mg was comparable in efficacy with 900 mg of Ibuprofen in the relief of pain related to osteoarthrosis. Toleration of the drugs was very good.