Seventy-seven patients with Kawasaki disease were prospectively evaluated from 1978 to 1983 to determine the sensitivity, specificity and predictive value for detecting coronary artery aneurysms with two-dimensional echocardiography. Seventy (91%) underwent selective coronary arteriography and are included in this report. The study was divided into two periods because of increased experience and the use of a systematic approach with two-dimensional echocardiography in the second period as compared with the first. Aneurysms were demonstrated in nine patients (13%). The coronary artery system was divided into six regions: proximal third of the main right coronary artery, distal right coronary artery, left main coronary artery, left anterior descending coronary artery, circumflex coronary artery and distal left coronary artery. The sensitivity and specificity were high when imaging the proximal regions, and improved from the first period to the second. Both sensitivity and specificity were lower for the more distal regions of the right and left coronary arteries. Overall, the sensitivity of two-dimensional echocardiography was 100% because there were no patients in our study who had isolated distal coronary artery aneurysms. Two-dimensional echocardiography is a sensitive and specific test for detecting aneurysms in the proximal portions of both the right and left coronary arteries, and is useful in selecting patients for invasive investigation with selective coronary arteriography.