Objective:To compare image quality of patients with different heart rate(HR) by 256-silce computed tomography coronary angiography(CTCA) using prospective electrocardiogram(ECG)-gating. Methods:Two hundred patients with suspected coronary artery disease underwent 256-slice CTCA using prospective ECG-gating. Patients were divided into two groups according to their HR: the first group(50 b.p.m≤HR < 70 b.p.m,n = 99) and the second group(70 b.p.m≤HR < 90 b.p.m,n = 111). Image quality was evaluated between those two groups. Results:Total 1410(94.95%)segments of the first group were evaluated,among which 1 123(79.65%) segments were classified as excellent,253(17.94%)were good and 34(2.48%) were bad. Total 1 571(94.35%) segments of the second group could be evaluated,1 208(76.89%) segments were classified as excellent,309(19.67%)were good and 54(3.44%) were bad. Conclusion:The patients with HR < 90 b.p.m can undergo CTCA using prospective ECG-gating. Image quality can satisfy the diagnostic requirement.