We describe a 76-year-old Japanese woman with primary systemic amyloidosis who presented with angina pectoris associated with ST-segment and T-wave abnormalities resulting from intramyocardial coronary artery amyloidosis. The patient was admitted to our hospital because of dyspnea and pretibial edema 7 years after the diagnosis of variant angina. A diagnosis of primary systemic amyloidosis (AL amyloid protein) was made after examination of gastric and endomyocardial biopsy specimens. The patient died of progressive, uncontrolled heart failure 3 months later. An autopsy study demonstrated only mild-to-moderate atherosclerosis in the epicardial coronary arteries. However, histological examination of the heart revealed diffuse stenoses and obstructions in the intramural coronary arteries by amyloid deposits. This patient had small-vessel coronary disease with ST-segment changes and angina caused by cardiac amyloidosis. A correct diagnosis of ischemic heart disease due to primary amyloidosis is important for estimation of the prognosis and for appropriate management.