The clinical course of a 4-month-old male infant with a dilated cardiomyopathy secondary to renal tubular losses of carnitine is outlined. He was admitted to the hospital with severe congestive heart failure. An echocardiogram demonstrated normal anatomy. The left ventricular shortening fraction measured 10%. A comprehensive cardiomyopathy evaluation was initiated. The total plasma carnitine level was only 25 mumol/ml, but the urine carnitine measured 434 nm/mg of creatinine. He was begun on oral L-carnitine and weaned from mechanical ventilation and inotropic support 10 days later. Two years later he remains asymptomatic with normal left ventricular function.