Congenital cardiac aneurysms are extremely rare. The echocardiographic features of this condition have never been described. The authors report a case of giant congenital left ventricular aneurysm wherein the diagnosis was made by echocardiography and confirmed at cardiac catheterization. The aneurysm was surgically removed. The histologic examination showed that the aneurysmal wall was only 1.5 to 2 mm thick but contained all the layers of the heart.