The hypothalamo-pituitary-gonadal axis was studied in 12 young women with manic-depressive or psychotic symptoms which obviously fluctuated in association with the menstrual cycle, and also in 36 psychiatric patients with other diagnoses. The hormonal features frequently observed among these 12 cases were elevated basal LH (8 of 12 cases), decreased basal FSH (6 of 12), elevated serum testosterone (6 of 12), androstenedione (5 of 12) and/or dehydroepiandrosterone-sulfate (3 of 11). These abnormalities resemble those of polycystic ovary syndrome (PCOS). An ultrasonographical study revealed polycystic changes in 8 out of the 12 cases. In 10 cases clomiphene citrate was administered, and was effective in 8. In comparison with the pathophysiology of PCOS, a possible relationship was suggested between the psychiatric problems and the PCOS-like hormonal abnormalities in these cases.