Fifty patients suffering from sports injuries were included in a double-blind trial comparing the efficacy and side-effects of naproxen and indomethacin. The patients' daily record cards showed that the number of patients whose paine cleared in less than seven days was statistically significantly greater in the naproxen grout (P = 0.03). Overall change at the seven-day follow-up visit, changes in the degree of pain, swelling and limitation of movement, as well as the number of patients ready for full activity at seven days were also greater in the naproxen group. However, the differences between the two groups of treatment did not reach statistical significance. The number of side-effects was equal in both treatment groups. One patient on indomethacin had to be withdrawn from the trial after two days' treatment, because of severe gastric pains.