In a case of double outlet right ventricle in a cat, initial examination revealed a holosystolic murmur and right-sided heart enlargement, as deduced from electrocardiography and thoracic radiography. On cardiac catheterization, it was determined that pressure in the right ventricle equaled that of the left ventricle. Angiography revealed a large ventricular septal defect, with prodominant left-to-right shunt and some right-to-left component. The cat lived for 3 1/2 years. During this period, the cat would become cyanotic only under stressful situations. At necropsy, the diagnosis was further refined to that of a double outlet right ventricle, as both the aorta and pulmonary artery originated from the right ventricle.