A 25-yr-old male captive walrus (Odobenus rosmarus divergens Illiger) died after suffering from periods of inactivity, anorexia, and weight loss for 8 wk. Necropsy revealed prominent, generalized atherosclerosis of cardiac arteries with widespread chronic myocardial infarction. Severe disseminated myocardial fibrosis most likely resulted in insidious cardiac failure that was ultimately the cause of death. Bouts of abdominal pain and disseminated cutaneous ulcers that had been observed 3 and 4 days before death, respectively, were attributed to circulatory failure and thrombosis. The cause of the vascular lesions remains unknown. When compared with humans, atherosclerosis is rare in animals and has not been described in a walrus.