Ninety-eight patients completed a double-blind, multidose, randomized parallel study in which buprenorphine (Temgesic) was compared to morphine. Drugs were administered at approximately equipotent intramuscular doses for a maximum of three days for the relief of moderate to severe postoperative pain. The two drugs exhibited similar profiles with pain relief evident at 1/2 hour, peaking at 1 hour, and decreasing to slight relief at 4-5 hours, with no significant differences for time to remedication. The most frequent side effect was somnolence. One patient suffered sudden chest pain shortly after an injection of morphine, and one patient had moderate hypoventilation after buprenorphine; both patients recovered uneventfully. Overall, both drugs provided good or excellent analgesia in 80 per cent of the patients in this unique multidose/observational study. Thus, these data and the reported lack of withdrawal symptoms and the absence of physical dependence liability suggest that buprenorphine may have a role in the management of chronic pain.