Objective    To investigate the role of preoperative peripheral blood CD4/CD8 ratio in predicting the prognosis of patients with coronary atherosclerotic heart disease (CAD) after off-pump coronary artery bypass grafting (OPCABG). Methods    A total of 118 patients with CAD who underwent OPCABG in our hospital from September 2016 to April 2017 were included in the study, including 82 males and 36 females aged 62.74±4.50 years. The primary end point was the incidence of major adverse cardiovascular events (MACE). Patients were divided into a high CD4/CD8 group (≥1.40, 62 patients) and a low CD4/CD8 group (<1.40, 56 patients) according to the results of flow cytometry. The correlation between CD4/CD8 ratio and prognosis of patients after OPCABG and the value of CD4/CD8 ratio for predicting postoperative MACE were evaluated. Results    Median duration of follow-up was 23.25 (20.91, 24.70) months, during which 21 patients (17.80%) experienced MACE and 4 patients (3.39%) were lost to follow-up. Kaplan-Meier analysis revealed that high CD4/CD8 group had a significantly higher MACE rate than the low CD4/CD8 group did (log-rank χ2=5.797, P=0.02). The results of adjusted Cox proportional hazards model showed that CD4/CD8 ratio (HR=3.103, 95%CI 1.557-6.187, P<0.01) was an independent risk factor of MACE in patients with CAD after OPCABG. The receiver operating characteristic curve showed that area under curve was 0.778 (95%CI 0.661-0.894, P<0.01), the optimal cut off value was 2.24, the sensitivity was 57.1%, and the specificity was 87.6%. Conclusion    Preoperative peripheral blood CD4/CD8 ratio is an independent predictor of MACE after OPCABG in patients with CAD.