This single-dose, double-blind, parallel-group, single-site study compared ibuprofen lysine 400 mg with acetaminophen 1000 mg and placebo in 240 patients with moderate-to-severe postoperative dental pain. The relative onset of analgesic response, overall analgesic efficacy, duration of effect, and safety were assessed over a 6-hour postdose period. Analgesic efficacy was assessed by patient self-rating of pain intensity, pain relief, time to meaningful pain relief, need for additional analgesic medication, and patient global evaluation. Both ibuprofen lysine 400 mg and acetaminophen 1000 mg were significantly (P < or = 0.05) more effective than placebo. Ibuprofen lysine had a significantly (P < or = 0.05) faster onset of action with greater peak and overall analgesic effect than did effect than did acetaminophen. All treatments were generally well tolerated.