This study was conducted to evaluate the effectiveness of mometasone nasal spray in preventing polyp relapse/symptom worsening in patients after surgical treatment of nasal polyps. Patients who met Screening eligibility underwent endoscopic sino-nasal surgery (FESS) on visit 2. Mometasone nasal spray or placebo was started about 2 weeks after surgery and continued for up to 24 weeks or until relapse.