Isolated ventricular noncompaction is a rare congenital disorder characterized by the presence of numerous prominent trabeculations and deep intratrabecular recesses which communicate with the ventricular cavity. This disease has a very bad prognosis. Two cases of isolated ventricular noncompaction in patients with chronic renal failure have been described. The first case is a 65-year-old male, on regular hemodialysis for 3.5 years due to mesangioproliferative glomerulonephritis. He was symptomless regarding signs of congestive heart failure, angina pectoris, systemic embolization or arrhythmia. The second case is a patient with chronic renal failure (due to renal calculosis) admitted because of non-ST elevation acute myocardial infarction. In both cases echocardiography revealed an enlarged left ventricle, with extremely thickened walls with two layers: a thin, compacted myocardium on the epicardial side, and a thicker noncompaction endocardial layer. Ratio between noncompaction part of the wall and compaction part was 2.56 in the first and 4.94 in the second case. Blood flow from the left ventricular cavity into recesses was recorded with Color Doppler. Oral anticoagulation therapy was introduced in both of them. Holter ECG in the first patient revealed an intermittent right bandle branch block and in the second patient, premature ventricular contractions. Neurological examination findings were normal in both patients. Echocardiography of first-degree relatives was performed in the first case and it was normal in all 5 relatives. In the second case it was not performed due to technical reasons (relatives live abroad). Regular echocardiographic follow-up of all patients with chronic renal failure is necessary in order to diagnose cardiovascular comorbidities including this rare abnormality and its complications.