OBJECTIVE: To determine the positive predictive value of the combined symptoms of severe dysmenorrhea with the sign of tenderness and/or nodularity of the cul-de-sac and/or uterosacral ligament(s) in diagnosing endometriosis clinically. MATERIAL AND METHOD: In this prospective study, 116 patients with severe dysmenorrhea, after excluding urinary and gastrointestinal disease, underwent pelvic examination by the same investigator. Women having adnexal mass on pelvic examination were excluded Tenderness, and also nodularity, of the cul-de-sac, right and left uterosacral ligament were recorded separately. The laparoscopist did not know the findings of the pelvic examination. The diagnosis of endometriosis was made visually when lesions were typical and all other lesions were biopsied. RESULTS: The prevalence of endometriosis was 78.4%. Tenderness, nodularity, tenderness and nodularity, and also tenderness or nodularity of cul-de-sac and/or uterosacral ligament(s) were all statistically significantly associated with the presence of endometriosis (P = .048, .005, .004, and .004 respectively). The positive predictive values were 85.5%, 94.0%, 94.6% and 86.7%, respectively. CONCLUSION: The positive predictive value of severe dysmenorrhea with nodularity of the cul-de-sac and/or uterosacral ligament(s) was 94.0%.