The safety and efficacy of single oral doses of oxaprozin (1200 mg), aspirin (650 mg), and placebo were compared in an 8-hour double-blind study of 105 patients with moderate to severe post-operative dental-surgical pain. As measured by mean and cumulative mean scores obtained with the pain intensity and verbal pain relief scales, both active drugs produced significantly (p less than 0.05) more analgesia than did placebo. A significantly (p less than 0.05) greater proportion of patients reported effective (moderate or better) pain relief in the oxaprozin and aspirin groups than in the placebo group at 2, 3, and 4 hours; significant (p less than 0.05) differences between the oxaprozin and placebo groups continued for the entire 8 hours. Oxaprozin provided more pain relief than aspirin during the latter part of the study. There were no statistically significant differences, however, in any of the efficacy assessments between the oxaprozin and aspirin groups. By the end of the 8-hour observation, significantly (p less than 0.01) fewer patients taking oxaprozin (27%) than placebo (60%) were considered treatment failures and needed a replacement analgesic. Of those taking aspirin, 41% were treatment failures, not statistically different from the proportion of treatment failures with placebo. Adverse effects were infrequent, mild, comparable between the active treatment and placebo groups, and not definitely related to drug therapy. Oxaprozin provided greater pain relief than placebo and was comparable to aspirin during the first 4 hours of the evaluation; thereafter, greater pain relief occurred in the oxaprozin-treated group than either the aspirin or placebo-treated group.