Hypogonadotropic hypogonadism with anosmia has been found in two brothers and a half sister, who are related through the same mother. Although the mother does not have the full syndrome, her history suggests she may have minor symptoms of the syndrome. X-linked inheritance seems most compatible with the familial distributions. Differences of this syndrome from other inherited hypogonadal conditions are discussed. The genetic defect is thought to directly or indirectly affect the hypothalamus which has associations with both olfaction and pituitary function. The importance of testing for anosmia in patients with abnormality in sexual development is noted.