OBJECTIVE Fragmented QRS (fQRS) as a predictor of cardiac events in coronary artery disease has previously been reported. In this study, we hypothesized that presence of fQRS on a 12-lead electrocardiogram (ECG) on admission would be predictive of adverse outcomes in non-ST elevated myocardial infarction (NSTEMI). METHODS A total of 149 NSTEMI patients (112 male, 37 female) were retrospectively analyzed. The fQRS pattern was defined as the presence of an additional R', notching in the nadir of the S wave, fragmentation of the RS or QS complexes in 2 contiguous leads corresponding to a major coronary artery territory. The relationship between presence of fQRS on admission on a 12-lead ECG, and primary end points [cardiovascular death (CVD)] and secondary end points (re-infarction, repeat target vessel revascularization [percutaneous/surgical]) were assessed. The median follow-up time was 18 (13-24) months. RESULTS Other than age, there were no significant differences in baseline characteristics and laboratory findings for patients in the fQRS and non-fQRS groups. The patients in the fQRS group were older [64 years vs 59 years, p=0.048]. CVD and re-infarction were significantly higher in the fQRS group in the median 18-month follow-up (26.1% vs 8.7%, p=0.005; 23.9% vs 10.7%, p=0.035, respectively). By a multivariate regression analysis in all 149 patients, age ≥65 years and the presence of fQRS in a 12-lead ECG on admission were found to be powerful independent predictors of cardiovascular mortality (HR: 4.91, 95% CI: 1.60-15.03, p=0.005; HR: 2.77, 95% CI: 1.02-7.50, p=0.044, respectively). CONCLUSIONS Presence of fQRS on a 12-lead ECG on admission is associated with increased long-term mortality in patients with NSTEMI.