This study was conducted to compare the effectiveness and safety of mometasone nasal spray once daily or twice daily with amoxicillin or with placebo in treating the signs and symptoms of acute rhinosinusitis. Patients received mometasone nasal spray 2 sprays per nostril once daily, 2 sprays per nostril twice daily, amoxicillin 500 mg three times a day, or placebo three times a day. Patients on nasal spray were treated for 15 days and patients on amoxicillin or placebo were treated for 10 days. All patients were followed-up with a 14-day no-treatment observation period.