There is little information on the sexual activity of patients with end-stage renal failure in spite of its being mentioned as a common side effect of kidney disease and chronic hemodialysis. In this report 32 married, male dialysis patients, 19 of whom had also received renal homografts, were interviewed and a detailed sexual history obtained. Twenty per cent of this population had no decrease in sexual functioning after the onset of kidney disease or the institution of dialysis, 45 per cent had reduced sexual potency after the onset of kidney disease, and another 35 per cent after beginning dialysis. Forty per cent of those patients receiving a kidney transplant had a subsequent increase in sexual potency.