Although endometriosis is usually diagnosed in reproductive aged women, adolescents after menarche may also effected by endometriosis. Since the diagnosis of all asymptomatic cases is impossible, the exact incidence of adolescent's endometriosis is not known. Chronic pelvic pain, dysmenorrhea, dyspareunia, pelvic mass and rarely infertility may be associated with adolescent's endometriosis. The exact diagnosis was performed by directly seeing endometriosis lesions. The most preferred method for this is laparoscopy (L/S). The L/S should be performed to the patients in whom chronic pelvic pain and dysmenorrhea are persistent despite medical treatment. The main goal of treatment is to decrease the severity of symptoms and to preserve the fertility. Nonsteroidal antiinflammatory drugs, oral contraceptives, progestins, cyproterone acetate, danazol and gonadotrophin releasing hormoneagonists are used for medical treatment. If the symptoms are resistant to the medical treatment, surgical treatment with L/S should be considered. The endometriosis lesions should be coagulated with electrocautery or laser.