BACKGROUND Cardiac involvement rarely occurs in classic hemolytic uremic syndrome (HUS); it is often fatal. METHODS The first patient, a 21-month-old boy, developed classic HUS with acute renal failure. Peritoneal dialysis was performed for 20 days. On the 10th day of dialysis, myocardial infarction occurred, probably related to coronary thrombus. The patient was given heparin and antibiotics because of an unexplained fever. The outcome was favorable despite antero-apical cardiac necrosis, and moderated chronic renal failure. The second patient, a 24-month-old girl, also showed a classic HUS, which required peritoneal dialysis for 10 days. Dilated cardiomyopathy with cardiac failure appeared on the 4th day of dialysis, not related to the volume overload and metabolic consequences of the acute renal failure, such as systemic hypertension or ineffective dialysis. On the 5th day of dialysis neurological involvement appeared. Neurological, cardiac and renal outcome was favorable. The third patient, a 25-month-old girl, developed a classical HUS, requiring peritoneal dialysis for 25 days. No cardiac insult appeared during the acute phase of the disease. After dialysis, the child had chronic renal failure (creatinine clearance: 15 mL/min/1.73 m2). Dilated cardiomyopathy appeared 3 months later, without definite etiology. The outcome was favorable with digoxin treatment. CONCLUSIONS A cardiac involvement should also be searched for in the acute phase of HUS and several months later.