Background: Approximately 20% patients with chronic rhinosinusitis undergoing Functional Endoscopic Sinus Surgery (FESS) experience impaired wound healing, leading to recurrences of sinusitis and polyps. Methods: We investigated the efficacy of oral+ local steroids in wound healing, following FESS in subjects with a chronic rhinosinusitis with/without nasal polyps. Ninety-nine subjects were randomised to receive 6 months' treatment with mometasone furoate nasal spray (MFNS) 200 mu g bid or placebo in double-blind manner approximately 2 weeks after FESS. Postoperative mean total score for several endoscopic parameters scores assessed at 6 months was calculated as the primary efficacy end-point. An endoscopic combination score (for inflammation, oedema, and polyps), a total symptoms score, and percent subjects requiring rescue medication, were assessed as secondary end-points. Results: MFNS led to greater, although not significant, reductions in total endoscopic scores in all subjects, compared with placebo. The combination scores, however, indicated significantly improved healing with MFNS than with placebo for all subjects (median scores: 0.0 vs 2.0, p = 0.02), and particularly for subjects with nasal polyps (median scores: 2.0 vs 4.0, p = 0.03). The total symptom scores and percent subjects requiring rescue medication were similar in the two groups. MFNS was well tolerated. Conclusions: These results suggest that treatment with MFNS following sinus surgery may improve wound healing, particularly in subjects with nasal polyps.