Objective: The aim of this study was to investigate which way of measuring blood pressure (BP), clinic, home or 24h-ABPM, can predict better left ventricular hypertrophy in the untreated hypertensive population. Design and method: 175 consecutive subjects (42% male) aged 57.9±14.9 years were included in the study. Subjects were never treated before for hypertension. All subjects underwent 24h-ABPM on a usual working day. Home BP monitor was provided to all patients for 7 days, while office BP was measured in the clinic using a mercury sphygmomanometer. Left ventricular hypertrophy was evaluated by a cardiologist with the use of a 3D echocardiography. Results: In the univariate analysis, only home systolic and diastolic BP were independently associated with left ventricular hypertrophy, while both clinic and 24hour systolic and diastolic BP found not to be. From ROC curves for left ventricular hypertrophy, AUC of home systolic BP monitor (0.758, p<0.05) was larger than that of 24h (0.538, p>0.05) and clinic BP (0.497, p<0.05). As regards DBP, the ROC curves suggest no discrimination for the different ways of BP measurement. Conclusions: Home systolic BP can be a better predictor of left ventricular hypertrophy in untreated population, when compared to 24h and office systolic BP. This result shows the importance of home monitoring for the prediction of left ventricular hypertrophy, even in the untreated population.