Background and Objectives : The clinical significance of white coat hypertension is still unclear. Moreover, no study has examined biochemical marker of myocardial fibrosis in white coat hypertensives. We compared target organ status in normotensive (NT), white coat hypertensive (WCH) and established hypertensive (EH) subjects. Methods : 25 NT, 17 WCH (ambulatory day time blood pressure < 135/85 mmHg) and 24 EH (untreated mild to moderate hypertension) subjects underwent extensive biochemical, echocardiographic and 24hr-urinary albumin excretion examination. The serum concentration of TGF-棺1 and the carboxy-terminal propeptide of procollagen type I (PIP), a marker of myocardial fibrosis, was measured by EIA (Enzyme immunoassay) method. Results : Compared with established hypertensives, the white coat hypertensives had significantly lower values of LV mass index (LVMI) (P=0.002). The mitral valve (MV) E/A ratio was lower in white coat hypertensives than in normotensives (P=0.05). The serum concentration of TGF-棺1 and PIP was significant higher in white coat hypertensives than in normotensives (P=0.01 and P=0.035, respectively) (see table) Conclusion : Our data indicate that patients with WCH represent an intermediate group between NTs and EHs in the aspect of target organ damage. Serum level of TGF-棺1 and PIP reflects the target organ damage in white coat hypertensives.