Background:Electrocardiographic parameters for the detection of left ventricular hypertrophy (LVH) asan independent cardiovascular risk factor and signifier end-organ damage in patients with hypertensionare known. The aim of this study was to evaluate the relation between QT interval parameters and LVH in patients with hypertension.Methods:This cross-sectional study recruited100 patients with primary hypertension who underwent cardiac echocardiography for the evaluationof left ventricular mass (LVM). Standard 12-lead electrocardiography was performed for all the patients,and QT interval parameters (QTmax, QTcmax, QTd[dispersion], and QTdF[difference between maximum and minimum QT intervals])were calculated. The data were analyzed using SPSS (version 18). The t-test wasapplied to assesstherelationship between QT parameters and left ventricular mass index (LVMI),and the receiver operating characteristic(ROC)curve was drawn to determine thecutoffpoint forthe mentioned electrocardiographictest.Results:The mean age ofthepatients was 60.52±9.74 years. The meanof QTd, QTmax,and QTcdin the patients with LVH was significantly greater thanthat of thepatients without LVH (P<0.05). ROC curve analyses of QT interval parameters showed thatthecutoffpointsfor QTmax, QTd, QTcmax,and QTcdvalues were420(specificity=0.79 and sensitivity=0.40), 50 (specificity=0.58 and sensitivity=0.76), 478 (specificity=0.29 and sensitivity=0.58), and 59 (specificity=0.65 and sensitivity=0.76), respectively. Conclusions:According to our findings, QTcdandQTcwould be better testsforthedetection of LVH. We recommend further research with larger sample sizes to obtain more generalizable findings. (Iranian Heart Journal 2015; 16(4): 35-40)