BACKGROUND: Coronary slow flow (CSF) phenomenon is described angiographically as delayed progression of the injected contrast agents through the coronary arteries. Aim of this study was to analyze ventricular repolarization in CSF patients by using Tpeak-Tend interval, Tpeak-Tend/QT ratio, Tpeak-Tend/QTc ratio and other repolarization parameters since these parameters are used as predictors for ventricular arrhythmogenesis. MATERIALS AND METHODS: We have retrospectively analyzed diagnostic coronary angiography results of 160 patients between 2010 and 2014. Patients were divided into two groups according to coronary flow results. CSF group consisted of 33 female, 82 male patients with mean age 51,9±11,5 years. Control group included patients with normal coronary flow; 13 female, 32 male with mean age 50,8±11,7 years. In all patients, ventricular repolarization parameters as well as other associated electrocardiographic intervals were measured on the twelve-lead surface electrocardiogram. RESULTS: The ventricular repolarization parameters: QTmax interval, QTmin interval, QTc, QTI, QTcI, JTmax interval, JTmin interval, JTdispersion and JTIndex were not significantly different between the groups. However followings parameters differed significantly between patients and controls; QRS (92,8±11,5 msn versus 78,3±16,713,40 msn, respectively; p=0.001), T wave (89±20,2 msn vs. 73,3±13,3 msn respectively, p=0.001), QT dispersion (26,8±17,5 msn vs. 13,5±20,4 msn respectively, p=0.002), JTcorrected (331,6±39,8%; vs. 350,1±39,7% respectively; p=0.01). Furthermore; Tpeak-Tend duration (89±20,2 msn vs. 73,3±13,9 msn respectively; p=0.001), T wave (204±34,9 msn vs. 189,2±24,8 msn respectively; p=0.003), Tpeak-Tend/QT ratio (0,22±0,05 msn vs. 0,19±0,03 msn respectively, p=0.001) were significantly higher in patients compared to controls. Tpeak-Tend/QTc ratio was also significantly higher in the CSF group compared to the controls. (0,21±0,05 msn vs. 0,17±0,03 msn respectively, p =0.001). CONCLUSION: Ventricular repolarization parameters are prolonged in patients with CSF.