Study objective: To evaluate the efficacy of an oral tramadol preparation versus that of an oral hydrocodone-acetaminophen preparation in acute musculoskeletal pain. Methods: A randomized, prospective, double-blind clinical trial was conducted in an urban teaching emergency department with an annual census of 41,000. Participants comprised a convenience sample of 68 adult ED patients with acute musculoskeletal pain caused by minor trauma. Thirty-three patients received tramadol (100 mg), and 35 patients received hydrocodone-acetaminophen (5 mg hydrocodone with 500 mg acetaminophen). The drugs were prepared in identical-appearing capsules. Pain was evaluated by a 100-mm visual analog scale (VAS) at baseline and at 30, 60, 90, 120, and 180 minutes after dosing. VAS scores were analyzed by 2-way repeated-measures ANOVA, and nominal data were analyzed by Fisher's exact test. Results: Mean pain scores did not differ at baseline (tramadol, 68.3 +/- 21.8; hydrocodone-acetaminophen, 69.1 +/- 17.8; P = NS) but were significantly lower in the hydrocodone-acetaminophen group beginning at 30 minutes through 180 minutes. There were 6 dropouts as a result of reported inadequate analgesia, 3 in each group (P = NS). The discharge diagnoses and prevalence of side effects did not differ significantly between groups. Conclusion: Tramadol provides inferior analgesia to hydrocodone-acetaminophen in ED patients with acute musculoskeletal pain.