Dissected interventricular septal aneurysm is a rare complication that occurs in conditions such as acute myocardial infarction, sinus valsalva aneurysm, infective endocarditis, thoracic trauma, pericardiocentesis and balloon angioplasty. Only two cases of dissected interventricular septal aneurysm secondary to coronary fistula have been described in the literature. Here, we present a case of dissected interventricular septal aneurysm secondary to congenital coronary fistula.