Secondary hypogonadism is not an infrequent abnormality in older patients presenting with the primary complaint of erectile dysfunction. Because of the role of testosterone in mediating sexual desire and erectile function in men, these patients are usually treated with exogenous testosterone, which, while elevating the circulating androgens, suppresses gonadotropins from the hypothalamic-pituitary axis. The response of this form of therapy, although extolled in the lay literature, has usually not been effective in restoring or even improving sexual function. This failure of response could be the result of suppression of gonadotropins or the lack of a cause and effect relationship between sexual function and circulating androgens in this group of patients. Further, because exogenous testosterone can potentially increase the risk of prostate disease, it is important to be sure of the benefit sought, i.e. an increase in sexual function. In an attempt to answer this question, we measured the hormone levels and studied the sexual function in 17 patients with erectile dysfunction who were found to have secondary hypogonadism. This double blind, placebo-controlled, cross-over study consisted of treatment with clomiphene citrate and a placebo for 2 months each. Similar to our previous observations, LH, FSH, and total and free testosterone levels showed a significant elevation in response to clomiphene citrate over the response to placebo. However, sexual function, as monitored by questionnaires and nocturnal penile tumescence and rigidity testing, did not improve except for some limited parameters in younger and healthier men. The results confirmed that there can be a functional secondary hypogonadism in men on an out-patient basis, but correlation of the hormonal status does not universally reverse the associated erectile dysfunction to normal, thus requiring closer scrutiny of claims of cause and effect relationships between hypogonadism and erectile dysfunction.