Magnetic resonance coronary angiography (MRA) was performed in 5 healthy volunteers and 13 patients to evaluate its diagnostic capability. Ten to 15 continuous cross sections were obtained for each coronary artery using fast cardiac cine MR (FASTCARD) with breath-hold, and reconstructed images were made. The control study showed good demonstration of the left main, proximal left anterior descending (Seg. 6) and proximal right (Seg. 1, 2) coronary arteries. Abnormal findings were classified as interruption, stenosis (severe or mild), irregularity, or decreased signal, and they were compared with the findings of conventional angiography in proximal segments (Seg. 1,2,5,6). Twelve of 15 lesions with significant stenosis (> 75%) were depicted as interruption or severe stenosis (sensitivity 80%). The sensitivity was 100% (6 of 6 lesions) in the right coronary artery and 67% (6 of 9 lesions) in the left coronary artery. The positive predictive value was 75% (12 of 16). Comparison at each segment revealed that the sensitivity, specificity and accuracy for interruption or severe stenosis were 92%, 79%, and 86%, respectively, for severe stenosis (> 90%), and 85%, 79%, and 83% for significant stenosis (> 75%). Interruption or severe stenosis on MRA is presumed to be an appropriate criterion for the detection of significant stenosis in the proximal coronary artery.