Efficacy and safety of the analgesic ciramadol in the management of postoperative pain was evaluated in 139 healthy patients given single, double-blind, intramuscular injections of either 30 mg ciramadol, 60 mg ciramadol, 10 mg morphine or 0.9% saline on the first or second postoperative day. Differences in pain intensity and relief of pain, changes from baseline on a pain analog scale, percentage of patients with moderate or greater pain relief, and cumulative treatment failures were measured for 6 hours after injection. Morphine proved to be superior to all other treatments. Neither dose of ciramadol could be statistically differentiated from placebo. During the first hour after administration, some measurements showed that 30 mg ciramadol was superior to 60 mg ciramadol. Patients experienced little or no drowsiness in any of the four groups, and other side effects were transient and required no specific therapy. Some patients experienced an acute increase in pain intensity after administration of 60 mg ciramadol; this possibly represents antagonism of the residual effect of the previous narcotic. This study must be interpreted with the knowledge that ciramadol, an agonist-antagonist analgesic, was administered to patients who had been receiving narcotic analgesics before entering the study. Future studies of ciramadol given as the sole analgesic may more clearly define its efficacy in the management of postoperative pain.