The authors carried out a perspective study to determine the frequency of silent ischemia (SI), in 50 consecutive patients with end stage renal failure, during dialysis by Holter monitoring. Twenty patients had SI. The number of cardiovascular risk factors, principally diabetes, smoking and the underlying renal disease was related to ischemic events. Dialysis may predispose to and facilitate the detection of myocardial ischemia by the simultaneous presence of hypotension, hypovolemia, hypoxia and tachycardia. Holter monitoring may allow the detection of ischemic events and the identification of a subgroup of dialytic patients with a high cardiovascular risk.