A two-yearold chlld with masslve cardlomegaly was proved to have restrlctlve cardlomyopathy. A llterature search has shown only two other cases of thls In young children. All three have had masslve blatrlal dllatatlon with nearly normal ventrlcular function. Thls case Is the first with clearly deflned echocardiography and compllcatlng dlagnostlc features assoclated with persistence of a left superior vena cava.