Flurbiprofen (Ansaid, Upjohn), a substituted phenyl propionic acid, is a new analgesic/anti-inflammatory agent. To evaluate its relative efficacy in noninflammatory pain, 159 hospitalized women with moderate or severe postpartum uterine cramps were given single oral doses of 50 mg of flurbiprofen, 650 mg of aspirin, 60 or 120 mg of codeine sulfate, or placebo in a parallel, stratified, randomized block, placebo-controlled, double-blind trial. Patients rated pain intensity, pain relief, and side effects in uniform interviews for six hours after treatment. All measures of peak and summed analgesia exhibited significant differences among the five treatments. Flurbiprofen and aspirin showed the greatest analgesic response and were significantly superior to placebo. Results of codeine treatment were equivocal with no evidence of a positive dose response. Side effects were unremarkable except for dizziness and drowsiness after the 120-mg codeine dose. These findings suggest that flurbiprofen as an analgesic for patients with postpartum uterine pain is equivalent to aspirin and superior to codeine.