BACKGROUND: Systemic hypertension is the commonest non-communicable disease in Nigeria. It is necessary to identify simple clinical and laboratory parameters to detect those with severe form of the disease. QTc dispersion reflects regional differences in ventricular repolarization.(QTcd = QTcmax - QTcmin). Prolonged QTc max and/ or increased dispersion ha ve been associated with increased cardiovascular mortality among patients with congestive cardiac failure, hypertrophic cardiomyopathy, rheumatic heart disease and left ventricular hypertrophy. AIM: The study examines whether QT intervals correlate with clinical, demographic and echocardiographic variables in newly diagnosed adult Nigerians with hypertension. METHODS: One hundred and forty subjects with systemic hypertension and 70 age- and sex-matched controls were studied. Demographic and clinical parameters were taken. QT parameters were measured on the surface electrocardiography (ECG). These were used to calculate QT dispersion (QTd) and corrected QT dispersion (QTcd). Echocardiographic parameters including fractional shortening, ejection fraction and left ventricular mass/index were obtained among the study population (Hypertensive subjects with normal QT, hypertensive subjects with prolonged QT and normal controls). Prolonged QTcd was defined as QTcd>80ms and prolonged QTc was defined as QTc>440ms. The differences between the groups were assessed using Chi square and independent samples t-test. RESULTS: Hypertensive subjects with prolonged QTc dispersion and prolonged QTc max. had a higher systolic blood pressure ( 152.4 ±12.1 vs. 150.98 ± 25.94, p=0.969), pulse pressure (62.85±24.19 vs. 59.46 ±24.14, p=0.709), left ventricular mass (188.24 vs 144.47, p=0.002) and left ventricular mass index (102.21 vs 84.52, p <0.001) than hypertensive subjects with normal QT max and normal QTc dispersion. There was positive correlation between QTc max and LVM(r=0.517,p<0.001) and LVMI(r=0.492, p=0.006). QTc dispersion correlated with LVM (r=0.485,p<0.001), LVMI (r=0.426,p=0.001) and sytolic blood pressure (r=0.246,p=0.001). In multiple regression analysis of the determinants of QT intervals, SBP and waist circumference showed the highest contribution among hypertensive subjects for QTcd while SBP, LVM, LVMI and BMI were significant predictors of QTc max. CONCLUSIONS AND RECOMMENDATIONS: QTc max and QTc dispersion are prolonged in hypertensive subjects than controls in the study. Among hypertensive subjects,these parameters (QTcmax and QTcd) were more prolonged in those with ECG-LVH, increased LVM and LVMI than those without. Aggressive antihypertensive therapy may reduce the increased risks due to prolonged QTc max and increased QTc dispersion