Studies fail to find uniform effects of age-related or induced hypogonadism on human sexual function. We examined the effects of induced hypogonadism on sexual function in healthy men and women and attempted to identify predictors of the sexual response to induced hypogonadism or hormone addback. The study design used was a double-blind, controlled, crossover (self-as-own control). The study setting was an ambulatory care clinic in a research hospital, and the participants were 20 men (average+/-SD age=28.5+/-6.2 years) and 20 women (average+/-SD age=33.5+/-8.7 years), all healthy and with no history of psychiatric illness. A multidimensional scale assessing several domains of sexual function was the main outcome measure. Participants of the study received depot leuprolide acetate (Lupron) every 4 weeks for 3 months (men) or 5 months (women). After the first month of Lupron alone, men received (in addition to Lupron) testosterone enanthate (200 mg intramuscularly) or placebo every 2 weeks for 1 month each. Women received Lupron alone for 2 months, and then, in addition to Lupron, they received estradiol and progesterone for 5 weeks each. The results of the study: in women, hypogonadism resulted in a significant decrease in global measures of sexual functioning, principally reflecting a significant decrease in the reported quality of orgasm. In men, hypogonadism resulted in significant reductions in all measured domains of sexual function. Testosterone restored sexual functioning scores in men to those seen at baseline, whereas neither estradiol nor progesterone significantly improved the reduced sexual functioning associated with hypogonadism in women. Induced hypogonadism decreased sexual function in a similar number of men and women. No predictors of response were identified except for levels of sexual function at baseline. In conclusion, our data do not support a simple deficiency model for the role of gonadal steroids in human sexual function; moreover, while variable, the role of testosterone in sexual function in men is more apparent than that of estradiol or progesterone in women.