With the aim of determining an effective therapy for adolescent women with endometriosis, the authors analyzed the results of laparotomy performed on 16 cases of female teenagers over a seven-year period. All patients, whose average age of menarche is 12.8, were diagnosed with endometriosis between two months and nine years after the menarche, with an average interval of 5.2 years. The chief symptoms are dysmenorrhea, pelvic pain and abdominal fullness. Of the three patients of unicornuate uterus with rudimentary horn, endometriosis was found only involving the adnexa on the side of the rudimentary horn, two of the three patients had absence of affected side kidney. Conservative operation including six cases of salpingo-oophorectomy and 10 cases of ovarian cystectomy were chosen followed by danazol treatment. One year to seven years after surgical treatment, two patients required subsequent conservative operation for recurrence of endometriosis and two other patients resumed dysmenorrhea. Two married women became pregnant 5 and 10 months after surgical and medical therapy respectively. In conclusion, adolescent endometriosis may occur around five years after menarche and an obstructive uterine anomaly, enhancing retrograde menstruation, increases the occurrence rate. The symptoms and treatment of endometriosis in teenage group do not really differ from that in the older women. In the treatment of endometriosis and for the prevention of recurrence, it is recommended to give three to six months of danazol after surgical treatment.