Objective To evaluate the curative effect of endscopic sinus surgery (ESS) and to investgate the causes and prevention of the complication of ESS.Methods 1800 patients with chronic sinusitis and nasal polyps were retrospectively analyzed by ESS treatment from Aug 1993 to Jun 2001.Results Patients with clinical types and stages from Ⅰ to Ⅲ were 171 cases(9 5%),1003 cases (55 7%),626 cases(34 8%) respectively.The clinical cure rate from Ⅰ to Ⅲ were 91 2%,71 1%,36 2% respectively.The total cure rate was 61 0%,complications were noted in 96 cases(5 3%).The types of complication included papyraceous lamina injury in 15 cases(0 83%),hemorrhage in 16 cases(0 89%),adhesion in 63 cases(3 5%),transient blindness in 2 cases(0 11%).Conclusions ESS is effective and safe in the treatment of chronic sinusitis and nasal ployps.The operation outcome is directly related to the typing and phasing of the disease.It is important to find and treat complications timely and accurately.