Few studies have examined the association between sex hormone serum levels, erectile function, and sex drive. Using data from the Olmsted County Study of Urinary Symptoms and Health Status among Men we examined the associations between sex hormone serum levels, erectile function, and sex drive. During 1989-1991, Caucasian men ages 40-79 years were randomly selected from Olmsted County, MN, and in the sixth year of follow-up questions on sexual function from the Brief Male Sexual Function Inventory were added and included biennially thereafter with assays for estradiol, testosterone, and bioavailable testosterone levels. Out of 414 men, 294 had a regular sexual partner and androgen measurements at the fourteenth year of follow-up. These cross-sectional results suggest the relationship between sex hormones and sexual function is complex. Total testosterone and erectile function were significantly correlated even after adjustment for age (r = 0.12, p = 0.04). Conversely, total testosterone was not significantly correlated with sex drive (r = 0.08, p = 0.17). Bioavailable testosterone was significantly correlated with both erectile function and sex drive (r = 0.16, p = 0.01 and r = 0.20, p = 0.001, respectively). However, these associations disappeared after age-adjustment (r = 0.04 and r = 0.09). This suggests that the age-related decline in sexual function may be due to age-related declines in levels of bioavailable testosterone rather than total testosterone levels.