A prospective search for episodes of silent myocardial ischaemia (SMI) was carried out during sessions of haemodialysis in 62 patients with chronic renal failure and was positive in 37.1% of the cases. The occurrence of SMI is correlated with the number of cardiovascular risk factors (p = 0.008) and particularly with diabetes (p = 0.012), smoking (p = 0.007) and age (p = 0.02), as well as with the type of nephropathy that had caused the renal failure (p = 0.02). During a 6-month follow-up two patients died; both had silent myocardial ischaemia on Holter recordings. In these anaemic patients, haemodialysis might sensitize the detection of ischaemia by the concomitant occurrence of hypotensive, hypovolaemic or hypoxic episodes, thus playing a aggravating role. The existence of such episodes characterizes a subgroup of patients at high cardiovascular risk for whom the prognosis and the best therapeutic approach remain to be determined.