End-stage renal disease (ESRD) affects sexual function. The etiology of sexual dysfunction in ESRD is multifactorial and hypogonadism is not uncommon. In a cohort of 96 men with ESRD, scores on International Index of Erectile Function (IIEF) correlated with bioavailable testosterone (T; P<0.01). We further evaluated the effects of administration of T on ED in hypogonadal men on hemodialysis. Nine men with ED and hypogonadism (baseline bioavailable T <3.82 nmol l(-1)), received 5 g T-gel (1% (10 mg g(-1)) per day treatment for 6 months. The IIEF and frequency of sexual intercourse per week were used to assess treatment efficacy. T administration significantly increased serum T levels to the normal range, and was associated with statistically significant improvements of the scores of the IIEF domains (erectile function from 7.6+/-8.0 to 12.8+/-7.8; intercourse satisfaction from 3.4+/-4.5 to 4.8+/-3.1; orgasmic function from 4.8+/-3.1 to 3.4+/-2.9; sexual desire from 3.4+/-2.9 to 4.4+/-0.6; overall sexual satisfaction from 2.6+/-1.3 to 3.8+/-1.0). But scores of the IIEF did not normalize. Frequency of weekly sexual intercourse increased from 0.4+/-0.4 to 1.1+/-0.8 (P<0.05) after 6 months. There were no adverse effects. We conclude that restoring T levels to normal in men with ESRD improved scores on the IIEF and frequency of weekly sexual intercourse.