Comparison of the analgesic effectiveness of dextropropoxyphene hydrochloride (Darvon-Lilly), codeine, aspirin, and placebo, alone and in various combinations, was accomplished using a-standard double blind technique. The 80 patients studied were seen daily and their subjective responses classified as "worse", "no change", and "better". Each agent was administered orally, in identical capsules, 2 to 4 times a day for 5 to 7 days until each had been received for 1 test period. Codeine, 32 mg, with aspirin, 325 mg, provided significantly better analgesia than the other agents studied. Approximately equivalent analgesia was obtained with dextropropoxyphene hydrochloride, 32 mg, with aspirin, 325 mg; codeine, 65 mg, and aspirin, 650 mg, codeine, 65 mg, was more effective than dextropropoxyphene hydrochloride, 65 mg. No significant toxic reactions or undesirable side effects were observed during the course of this study.