Subvalvar left ventricular aneurysm is a rare disease of unknown etiology, that has been described most often in black Africans. A case of Brazilian indian with heart failure and a murmur of mitral regurgitation is reported. The chest x-ray showed a mild bulge in the left cardiac border and two-dimensional echocardiography demonstrated submitral left ventricular aneurysm, confirmed by left ventricular angiography. Surgical treatment consisted of resection of the aneurysm and mitral valvuloplasty. A perforation of the aneurysm, undetected neither by two-dimensional echocardiography nor by angiography was found at surgery.