Among 108 patients with cardiac amyloidosis studied at autopsy between 1889 and 1977 there were 5 (4.6 percent) with severe occlusive amyloid deposits in intramyocardial arteries. The hearts of all five patients showed focal subendocardial ischemic injury, and the vessels supplying these areas had either complete or near complete luminal obliteration by amyloid. Clinically, four patients had congestive heart failure; one of these patients also had arrhythmias and one had angina pectoris. Neither the clinical nor the pathologic features of ischemic heart diseases could be attributed to disease of the epicardial coronary arteries. Amyloidosis of the intramyocardial arteries appears to be capable of producing localized areas of ischemic necrosis and may produce intractable congestive heart failure due to multiple areas of ischemic injury.