A double-blind controlled trial was carried out in 18 in-patients with classical or definite rheumatoid arthritis to assess the effectiveness of night-time medication with 100 mg indomethacin plus 10 mg diazepam, 200 mg sulindac, and 200 mg sulindac plus 10 mg diazepam in improving sleep and reducing night pain and the duration of morning stiffness. Patients received each treatment regimen for 1 night. The results from the 17 patients completing the full trial protocol indicated that indomethacin plus diazepam was the most effective of the three regimens, although the differences did not reach conventional statistical significance. It is suggested that in further such studies with sulindac a larger dose and a longer duration of treatment should be used.