The aim of this prospective, multicenter, randomized, double-masked clinical trial was to compare the efficacy and safety of moxifloxacin with those of cefuroxime axetil for the treatment of community-acquired acute sinusitis. Five hundred forty-two adult patients with symptoms and radiographic evidence of acute maxillary sinusitis received a 10-day oral regimen of either moxifloxacin (400 mg once daily) or cefuroxime axetil (250 mg twice daily). Acute signs and symptoms at presentation had lasted >7 days but <4 weeks. Clinical response at the end of therapy (7 to 14 days after treatment) was the primary efficacy variable. Four hundred fifty-seven of the patients (223 moxifloxacin, 234 cefuroxime axetil) were included in the clinical efficacy analysis. Moxifloxacin was found to be similar in effectiveness to cefuroxime axetil at the end-of-therapy visit (90% vs. 89%, respectively; 95% confidence interval, -5.1% to 6.2%). Clinical relapse at the follow-up visit was reported for only 8 patients (3 moxifloxacin, 5 cefuroxime axetil). No clinically significant differences were observed with respect to the number of patients experiencing a successful clinical response based on demographic or infection characteristics. Five of the 542 enrolled patients were lost to follow-up. Of the 537 patients in the intent-to-treat population, drug-related adverse events were reported in 37% of moxifloxacin-treated patients and in 26% of cefuroxime axetil-treated patients (P = 0.006). Adverse-event profiles were comparable in the 2 treatment groups, with the exception of nausea, which was reported by 11% of moxifloxacin-treated patients compared with 4% of cef uroxime axetil-treated patients (P = 0.003). In this study, moxifloxacin was as effective as cefuroxime axetil in the treatment of community-acquired acute sinusitis.