In two 46,XX males, 20 and 21 yr of age, gonadotropins, testosterone, and estradiol were measured in serum and compared to those in a control group of four men. In addition, in one subject, androgen metabolism was measured in biopsied skin and cultured skin fibroblasts. In both XX men, a pulsatile pattern of gonadotropin, testosterone, and estradiol release into serum was observed. The levels of the gonadotropins and estradiol were higher and the levels of testosterone were lower in XX men than in normal men. hCG stimulation resulted in a significant increase in testosterone secretion, and LRH administration caused a more prolonged rise in gonadotropin levels in the XX men. The administration of estradiol caused a positive feedback response in the XX men and resulted in a suppression of gonadotropin secretion in the controls. Finally, the formations of C-19 metabolites from testosterone and estrone from androstenedione were found to be in the same range in skin and skin fibroblasts from the XX men as in those from normal men. It can be concluded that 46,XX men have altered hypothalamic-pituitary and gonadal function compared to normal men.