A double-blind clinical study comparing a new non-narcotic analgesic, nefopam, with pentazocine was carried out on 50 Indian patients. Forty patients had undergone surgical procedures, and the remaining 10 had musculoskeletal or traumatic disorders. There were 25 patients in each group. It was observed that both drugs were capable of relieving post-surgical pain which was either very severe (score 4) or severe (score 3). Their efficacy was comparable. In patients who had an initial pain score of 4, a significant (p less than 0.05) fall in the sum of pain intensity scores (SPIS) occurred in two days. For an initial pain score of 3, a correspondingly significant fall in SPIS took three days. These results were statistically significant (p less than 0.01). Nefopam had a significantly better side effect profile than pentazocine. In the nefopam group, 4/25 patients had side effects, as opposed to 10/25 in the pentazocine group (p less than 0.05, Fisher's exact probability test). It was also noted that the incidence of side effects was greater in the pentazocine group (61) than the nefopam group (22), the difference being statistically highly significant (p less than 0.001, chi 2-test). A few patients (score 4) in both groups required additional morphine as relief analgesic on the first day of therapy. Thus the non-narcotic nefopam is equally effective as the narcotic pentazocine and has less side effects.