Background: Early diagnosis and identification of high-risk non-ST elevation myocardial infarction (NSTEMI) is an important issue. Fragmented QRS (fQRS) complexes are defined as various RSR' patterns on 12-lead resting electrocardiography (ECG). Previous studies revealed that fQRS is related with increased ventricular arrhythmias and cardiovascular mortality. The relation between fQRS and mortality in acute coronary syndromes, mitral valve disease severity and structural heart disease has been shown in different studies. The aim of this study was to investigate relation between fQRS and long-term cardiovascular mortality in NSTEMI patients.