Objective: Electrocardiography is used in the initial risk assessment of patients with non-ST- elevation myocardial infarction. The frontal QRS-T angle is an electrocardiography parameter that may be affected by the alterations in the coronary blood flow. This study aimed to explore the relationship of the frontal QRS-T angle with coronary flow grade and adverse events in non-ST-elevation myocardial infarction patients. Methods: A total of 191 non-ST-elevation myocardial infarction patients were divided into 2 groups based on the thrombolysis in myocardial infarction (TIMI) flow level on coronary angiography before revascularization, namely TIMI 0/1 and TIMI 2/3. The frontal QRS-T angle obtained before revascularization was compared between the groups and its relationship with adverse events was examined. In-hospital all-cause mortality, repeat target lesion revascular- ization, new-onset heart failure, ventricular arrhythmias, and atrial fibrillation were defined as adverse events. Results: Frontal QRS-T angle was wider in the patients with TIMI 0/1 flow compared to the patients with TIMI 2/3 flow (P < 0.001). The frontal QRS-T angle was determined to be a predictor of TIMI flow grade 0/1 before revascularization in patients with non-ST-elevation myocardial infarction (odds ratio: 1.51; 95% CI: 1.30-1.75; P < 0.001). The frontal QRS-T angle was a predictor of the adverse events during hospitalization in the patients with non-ST- elevation myocardial infarction (odds ratio: 1.11; 95% CI: 1.04-1.19; P = 0.002). The cut-off values of the frontal QRS-T angle for TIMI flow grade and adverse events were determined to be 73.5°, based on receiver operating characteristic curve analysis. Conclusion: Increased frontal QRS-T angle may be a useful electrocardiography parameter for determining TIMI flow grade and the need for an early invasive strategy in patients with non- ST-elevation myocardial infarction.