Abstract: Objective: To investigate the feasibility of prospective coronary computed tomography angiography (CTA) using tube voltage of 80 kVp in patients with low body mass index (BMI). Methods: Eighty-four patients with suspected coronary artery disease (CAD) underwent prospective ECG-gate coronary CTA. The cases were divided into two groups based on BMI: One group (BMI ≤ 22kg/m²) was examined with 80 kVp, and the other group (22< BMI ≤25) with 100 kVp. If heart rates < 65beats/min, pulse exposure time was set at 200 ms, otherwise 380ms. The imaging qualities of coronary artery segments with diameter ≥1.5 mm were evaluated. Image quality and radiation dose were compared between groups. Results: The age, height, and heart rate were insignificantly different between groups. In the 80 kVp and 100 kV groups, the EDs were 0.56 ±0.21 and (1.43 ±0.58) mSv, respectively. There were significant differences in CT dose index volume (CTDIvol), dose length product (DLP) and ED between groups. The image quality rates (score of 3 or 4) were 92.2% and 91.8% in the 80 kVp and 100 kVp groups, respectively. In image quality scores, aortic SNR and coronary trunk CNR had no significant differences between two groups. Conclusion: Prospective coronary CTA using tube voltage of 80 kVp in low-BMI patients can provide adequate coronary diagnostic information; while significantly reduce the radiation dose.