Endometriosis is the most common cause of secondary dysmenorrhea among adolescents. Data on postoperative symptoms of the disease in adolescents are limited. In this study we aimed to describe the clinical characteristics and postoperative symptoms of adolescent endometriosis in our center. Retrospective cohort study. Tertiary care institution. Eighty-five adolescents with surgically confirmed endometriosis, age younger than 19years, were included. None. Clinical characteristics including demographic factors, pelvic symptoms, and changes of pelvic pain after surgery. Of 11,236 patients with endometriosis who received surgical treatment between January 2008 and January 2018 in our department, 85 adolescents (85/11,236; 0.76%) were included. The mean age at the time of surgery was 16.3 (±2.4) years and pelvic pain was the main symptoms which occurred in 73/85 (85.9%). Forty-four of the 85 patients (51.8%) had associated genital malformations. The patients with genital malformations tended to present with a younger age at the time of surgery (15.1±2.4 vs 17.6±1.7years; P<.001) and a shorter duration of symptoms to time of surgery (1.5±1.3 vs 2.3±2.1years; P=.033). The median follow-up time was 56months (range, 24-140months) after surgery, and the pelvic pain had disappeared in 41.7% of patients, improved in 38.3% of patients, and had no change or worsened in 20.0% patients. Pelvic pain was the main symptom in adolescents with endometriosis and was greatly improved after surgery. It should also be noted that genital malformation might be an important factor in younger adolescents with endometriosis.