OBJECTIVE Home blood pressure (HBP) measurements are known as an important adjunct to office blood pressure (OBP) measurements in clinical practice. But little is known about the relationship between HBP and subclinical target organ damage (TOD) other than left ventricular hypertrophy (LVH). So we investigated the relationship of HBP measurements with subclinical TOD in untreated hypertensive patients. METHODS We measured ambulatory blood pressure (ABP), HBP and OBP of 93 untreated hypertensive patients (men: 60 and women: 33, mean age, 49±13 years). The ABP was recorded for 24 hours, HBP was measured for one week, and OBP was measured at least in two visits. All BP measurements were taken using automatic BP measuring device. The parameters indicating subclinical TOD were the left-ventricular mass index (LVMI) by transthoracic echocardiography, urinary albumin excretion rate (AER), brachial ankle pulse-wave velocity (PWV), and carotid intima-media thickness (IMT). RESULTS The LVMI was significantly correlated with systolic HBP and 24 hours systolic ABP, but not with OBP. The AER, PWV and IMT were also significantly correlated with systolic HBP and 24 hours systolic ABP. In a binary logistic regression analysis, systolic HBP, 24 hours systolic and diastolic ABP were the predictors of LVMI, AER and PWV (all p<0.05). CONCLUSIONS Our data suggest that HBP is as good as ABP monitoring and superior to OBP measurements in regard to their association with subclinical TOD. Therefore, HBP measurements give valuable information on the subclinical TOD in hypertensive patients in addition to ABP monitoring.