Background: Endoscopic sinus surgery has been used for diagnosis and treatment of chronic inflammatory diseases of paranasal sinuses since recent years.

Materials and Methods: In this study 104 patients with chronic sinusitis (with or without polyps) which were managed with endoscopic sinus surgery (ESS) were followed for 6 to 24 months after surgery (24 patients refused to continue follow up) and the recovery rate of symptoms were evaluated.

Results: The effectiveness of this therapy is statistically approved and the most important symptom which diminished was nasal obstruction (from 95 percent to 18.5 percent), the least important symptom which diminished was anosmia (from 57 percent to 21 percent).

Conclusion: This study confirmed the efficacy of functional endoscopic sinus surgery in improvement of chronic sinusitis symptoms.