Endoscopic sinus surgery (ESS) is a method used with success in the treatment of chronic inflammatory paranasal sinus diseases. Between February 1991 and June 1995 the Messerklinger technique for ESS was used in 415 patients who had been pre-operatively evaluated in detail according to the staging. system used in our clinic. Average post-operative follow-up was 23 months. Our general success rare was found to be 86.3% upon evaluating the subjective improvements in the patients' symptoms in the post-operative period. The major and minor complication rates in our series were 0.24 and 20.24%, respectively.