Objective: Raised blood pressure is a key risk factor for target organ damage (TOD). The relationship of behavioral aspects of blood pressure measurements and TOD in untreated essential hypertensives has not been established. Methods: Four hundred fourteen subjects (M:F = 222:192; mean age, 48 짹 12 years) with untreated hypertension underwent office BP (OBP) , Home BP monitoring (HBPM), 24-hour ambulatory BP monitoring (24h ABPM) and central BP (CBP) at multicenter. And we assessed BP variability from the SD. TOD was evaluated by ECG, echocardiography, carotid ultrasonography, detection of microalbuminuria and bilateral fundus examination. TOD was defined by the presence of microalbuminuria and ultrasonographic evidence of cardiac and vascular alteration. Results: 76(18%) subjects (M:F = 38:38; mean age, 50 짹 12 years) showed TOD; 23 left ventricular hypertrophy; 19 microalbuminuria; 4 cerebrovascular disease; 21 cardiovascular disease; 3 peripheral artery disease; 4 retinopathy; 32 carotid artery alteration. There were significant differences in systolic OBP (151 짹 16 vs 145 짹 15 mmHg, p=0.005), daytime (143 짹 16 vs 137 짹 12 mmHg, p=0.003) and nighttime (142 짹 16 vs 137 짹 12 mmHg, p=0.028) systolic BP, systolic BP (143 짹 15 vs 137 짹 11 mmHg, p=0.007) on HBPM, systolic (14.6 짹 6.2 vs 9.6 짹 4.1 mmHg, p<0.0001) and diastolic (11.0 짹 4.0 vs 8.4 짹 3.2 mmHg, p=0.001) BP variability, nighttime systolic (11.8 짹 4.2 vs 9.0 짹 3.9 mmHg, p<0.0001) and diastolic (9.1 짹 2.9 vs 7.9 짹 2.7 mmHg, p=0.014) BP variability, morning systolic (133 짹 14 vs 126 짹 14 mmHg, p=0.003) BP on 24h ABPM in the untreated essential hypertensives with and without TOD. Receiver operating characteristics curve analysis yielded a sensitivity and specificity of 79% and 60%, respectively, with 24hr systolic BP variability cut-off value of 8.0 mmHg for prediction of TOD (Figure). Conclusions: 24hr systolic BP variability among behavioral aspects of blood pressure measurements is closely related to TOD in untreated essential hypertensives.