The purpose of this study is to evaluate the incidence of endometriosis and tuboperitoneal fistula in remaining tubal segments after tubal ligation. We reviewed 936 tubes which were obtained from 474 patients who received tubal reanastomosis in the Department of Obstetrics and Gynecology in Seoul National University from June, 1980 to June, 1986. The results were as follows: 1. The incidence of tuboperitoneal fistula was 9.31% of the total 936 tubes (87 tubes) and cautery was the most frequent technique of sterilization in fistula formation (15.20%). 2. The incidence of tubal endometriosis was 2.03% of the total 936 tubes (19 tubes) and cautery was the most frequent technique of sterilization in the development of tubal endometriosis (2.73%). 3. The incidence of tuboperitoneal fistula in the remaining proximal tubal segment within 4 cm was 11.25% and the incidence of endometriosis in the remaining proximal tubal segment above 4cm was 5.54%. 4. The incidence of tuboperitoneal fistula within 3 yrs after tubal ligation was 11.92% and the incidence of endometriosis over 6 yrs after tubal ligation was 5.73%.