The persistence of myocardial sinusoids in both ventricles as an isolated anomaly is described. A 21-year-old patient had progressive heart failure considered as cardiomyopathy of obscure etiology. Two-dimensional echocardiography demonstrated channel-like structures in the thickened myocardium of both hypokinetic ventricles. Angiography showed a honeycomblike inner contour in both ventricles. Autopsy proved the diagnosis of persistent sinusoids in a thickened myocardium.