An investigation to determine the comparative value of pain-relieving drugs conducted on 94 private patients who had undergone orthopedic surgery was started 48 hours postoperatively and continued for three days. Four substances were used: dextro propoxyphene hydrochloride, 1 00 mg.; codeine phosphate, 65 mg.; meperidine hydrochloride, 100 mg.; and placebo. Capsules were administered at four-hour intervals. Intensity of pain was scored and interrogation of patients was done by a physician. The drugs were found to be significantly more pain-relieving than was the placebo. The analgesic effectiveness of the drugs in the doses used was indistinguishable. The over-all analgesic effectiveness of drugs and placebo- was similar to that found by other workers. A separate study on placebo effect showed that the patients discriminated more accurately between analgesics and placebos on the first day of study than on subsequent days.