After the discovery of sleep apnea in 2 patients receiving chronic maintenance hemodialysis, we decided to survey all 29 male patients undergoing outpatient dialysis for symptoms suggestive of sleep apnea. 12 of 29 (41%) had positive clinical histories. 8 of these patients consented to undergo all-night polysomnography. 6 were found to have sleep apnea which was primarily obstructive in type. Recent information has implicated testosterone administration in the development of obstructive sleep apnea. Therefore, polysomnography was performed in 5 of the patients both on and off weekly testosterone injections which they were receiving to stimulate erythropoiesis. There was no change in sleep complaints or a decrease in the number of apneas and hypopneas off therapy. Sleep apnea should be considered in symptomatic male dialysis patients. Its causation is presently unknown but it does not appear to be solely related to the administration of testosterone.