A double blind randomized study was done to compare Nalbuphine 20 mg I.M. to pentazocine 30 mg I.M. for postoperative pain relief after orthopedic surgery. This dose of pentazocine was choosen according to reports in the literature and to our standard practice. Sixty patients entered the study and were observed regularly till up 6 h post injection. The test drug was given when a pain score of 6 was shown on a VAS from 0 to 10. Onset, duration and quality of pain relief were significantly superior for nalbuphine with 50% of the patients still having no or only moderate pain at the end of the observation period. Cardiovascular and side effect were in both groups minor.