The endocrine system is in a state of so-called dynamic cquilibrium, having reciprocal relationship each other, hence maintains normal menstrual cycle. Of all the pituitary-ovarian, -adrenal, and -thyroid systems, the first is the one directly related to the normal menstrual cycle. For the diangosis and treatment of patients who have adnormal menstrual cycle, mostly anovulatory patients, each endocrine function and the relationship between each endocrine glands should be evaluated. Various schemes have been proposed by many investigators for the functional evaluation of pituitary-ovarian system, however, it still remains undecisive. The author selecter patients who had abnormal menstrual cycle and were considered to have abnormality in pituitary-ovarian-uterine system on the basis of the detail history, clinical symptoms and signs, various clinical examinations such as B.B.T., cervical mucus test, endometrial biopsy and B.M.R., and tried to find the causative organ of abnormal cycle by measuring the urinary excretion amount of gonadotorphin, estrogen, pregnanediol, 17-ketosteroids, 17-hydroxycorticosteroids as well as by the response to the administration of various hormones, especially gonadotrophin. The results obtained from this study were as follows: 1) Abnomal menstrual cycle was found in 208 cases out of 2311 gynecological patients, of whom 57 cases were with amenorrhea(2.5%), and 151cases were with irregular cycle(6.5%). Among 57 amenorrhea cases, 6 patients were with primary, and 51 patients were with secondary amenorrhea. 2) The amount of various hormones in urien of women with normal menstrual cycle were quantitatively determined: Gonadotrophin, GA M±σ=203±101γ/day, GB M±σ=73±40γ/day, biologically 6-50 m.u.u./day; Estrogen M±σ=95.7±15.7γ/day; Pregnanediol M±σ=4.68±0.75mg/day; 17-Ketosteroids M±σ=11.9±3.44mg/day, and 17-Hydoxycorticosteroids M±σ=108±0.27mg/day. 3) Based on the results of hormone assay and B.B.T., the abnormal menstrual cycle was grossly divided in two groups, amenorrhea and irregular cycle. Amenorrhea was again classified into central, ovarian, uterine and other origins. Amenorrhea with central origin was subdivided into pituitary and psychogenous (or environmental) origins. Irregular cycle was classified into anovulatory irregular cycle, lutein function insufficiency and ovulatory irregular cycle. Anovulatory irregular cycle and lutein function insufficiency were subdivided into oligomenorreha and polymenorreha respectively. On the basis of hormone assay, amenorrhea and anovulatory oligomenorrhea were again classified as beiow. Ⅰ) Type Ⅰ(Hypopituitary type): Low gonadotrophin, low in all or a part of estrogen, 17-KS, 17-OHCS. Ⅱ) Type Ⅱ(Primary hypogonadism type): Marked high gonadotrophin. Ⅲ) Type Ⅲ(Psychogenic type or Environmental type): Low or normal gonadotrophin, high 17-OHCS. Ⅳ) Type Ⅳ (Normal type): Hprmone assays were normal. Ⅴ) Type Ⅴ (Excessive androgen type): 17-KS level was especially high. Ⅵ) Type Ⅵ (Adrenal type): Low 17-OHCS. Ⅶ) Type Ⅶ (Others): Abnormal metabolism, thyroid insufficiency. 4) Analysis of pituitary-ovarian function: Since the complete differentiattion of causative organ of abnormal menstrual cycle was considered to be difficult by the above hormone assay only, the final determination should be made by the ovarian reponse to the exogenous gonadotrophin. High urinary gonadotrophin and low estrogen level were attributed to primary hypogonadism, and the low urinary gonadotrophin and low estrogen level were considered as the result of hypogonadotrophic hypogonadism if the estrogen level was elevated, pregnanediol was demonstrated and B.B.T. became biphasic by the exogenous gonadotrophin.