This study was performed to determine the effect of maintenance hemodialysis and successful renal transplantation from living-donor on the reproductive potential of men with ESRD. In 19 men (18-47 yr old) with ESRD the plasma level of testosterone follicle stimulating hormone (FSH), luteinizing hormone (LH) and prolactin were determined and semen analyzed six month after hemodialysis and again six month after successful renal transplantation. Four patients who had severe oligospermia underwent testicular biopsy 6 month after hemodialysis and again 6 month after successful renal transplantation. During hemodialysis levels of testosterone were low in 7 patient and levels of FSH and LH were elevated in 13 and 12 patients respectively. Serum prolactin was elevated in 6 patients. Semen analysis has revealed moderate and severe oligospermia in 9 patients, impaired motility, morphology and volume of semen in 14, 10 and 6 patients respectively. Four patients with severe oligospermia underwent testicular biopsy that revealed late maturation arrest. After renal transplantation semen parameters improved including: sperm density in 5, motility in 6, morphology in 4 and volume of semen in 4 patients. Improvement of sperm count, motility and morphology was statistically significant (p < 0. 05). Unfortunately testicular biopsy underwent only in one patient that revealed normal spermatogenesis. After renal transplantation testosterone level became normal in 5 patients, FSH in 3 patients, LH level in 6 patients and prolactin level 3 patients. The normalization of testosterone, FSH and LH levels after transplantation were statistically significant (p < 0.05). Semen quality after transplantation (in contrast with haemodialysis) improved in six patients that was statistically significant (p < 0.05). The impairment of testicular function seen in advanced uraemia is not reversible by hemodialysis in contrast after successful renal transplantation, testicular function showed a striking if incomplete recovery. Thus the restoration of reproductive function after successful renal transplantation is a realistic expectation for men with chronic renal failure.