BACKGROUND Although coronary artery bypass graft surgery (CABG) has been proven to have mortality and morbidity benefits in patients with non-ST elevation myocardial infarction and multivessel disease, the appropriate timing of this procedure remains unclear. Therefore, we proposed a propensity score-matched analysis comparing the clinical outcomes between patients who underwent CABG within the first 48 h of admission (early CABG) and patients who underwent CABG after 48 h of admission (delayed CABG). METHODS Using the largest inpatient care database in the USA, the Nationwide Inpatient Sample, we identified patients with a primary diagnosis of acute myocardial infarction using the ICD 9-DM diagnosis codes. We then performed propensity score-matching analysis to control for 24 possible confounders. RESULTS We identified 31 969 patients in the Nationwide Inpatient Sample database with a primary diagnosis of acute myocardial infarction who underwent CABG. The mean age of the cohort was 64.5±11.5 years and 33.4% were female. After performing propensity-matching analysis, we obtained a subset of 1555 patients in each group, with a mean age of 64.7±10.1 years; the male to female ratio was ~4 : 1. The incidence of hemorrhage, shock, and cardiac, pulmonary, and renal complications was comparable between the two groups. The incidence of mortality was not statistically significant between the two groups (2% in the early CABG vs. 1.8% in the delayed CABG, P=0.695). The mortality risk factors were as follows: age more than 70 years [odds ratio (OR): 3.42, 95% confidence interval (CI): 1.85-6.34, P<0.001]; cardiogenic shock (OR: 3.22, 95% CI: 1.35-7.67, P=0.008); and mechanical circulatory support with balloon counterpulsation (OR: 2.93, 95% CI: 1.45-5.90, P=0.003). CONCLUSIONS CABG performed within 48 h of admission does not significantly increase the risk for in-hospital mortality compared with undergoing the procedure after 48 h of admission in propensity-matched patients.