Objective: The aim of the study was to evaluate the diagnostic accuracy and effective radiation dose (ERD) of high pitch dual source multidetector computed tomography (MDCT) for coronary artery bypass graft (CABG) patency. Materials and methods: Fourty-five patients who underwent 128 × 2‑slice MDCT angiography with a prospective electrocardiogram-triggering, low-dose, high pitch, dual source, flash spiral acquisition mode after CABG surgery were included in the study. The interobserver agreement of the image quality was evaluated with Cohen κ value. The image quality was compared to the heart rates (HRs) using Mann–Whitney U test and to the graft segments using χ 2 test. The findings for the CABG patency on MDCT were compared to those determined on catheter coronary angiography. Dose-length product (DLP) and ERD were compared to the gender, HRs, and body mass index (BMI) of the patients using Kruskall Wallis and Mann–Whitney U tests. Results: A total of 110 grafts and 330 vessel segments were evaluated with a good interobserver agreement (κ = 0.80). The image quality was better in proximal and middle graft segments (p < 0.05), as well as in the patients with low HRs (p < 0.05). High pitch MDCT had the following sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy for evaluation of graft patency: 92.8, 99.3, 92.8, 99.3 and 98.8 %, respectively. ERD was correlated to the HRs and BMI. Conclusions: High pitch 128 × 2‑slice dual source CT angiography is a noninvasive imaging modality, and it can be safely and effectively used in evaluation of CABG patency with lower radiation dose.