OBJECTIVE: Blood pressure (BP) measured at clinic is hard to see the BP at home and predict an existence of white coat hypertension or masked hypertension. Therefore, the study was done to see whether the blood pressure difference measured by nurse and physician at clinic may predict white coat effect in treated hypertension. METHODS: A total of 1,087 outpatients (5710year, female; 52%) with chronically treated hypertension in university hospitals were enrolled. Patients were classified into 4 groups according to hospital (���140/90 mm Hg) and home (���135/85 mm Hg) BP levels; controlled hypertension (CH: low hospital and home BP), white-coat hypertension (WCH: high hospital but low home BP), masked hypertension (MH: low hospital but high home BP), and uncontrolled hypertension (UH: high hospital and home BP). White coat effect was defined as a difference of physician���s BP -home BP. RESULTS: BP difference between nurse and physician was -1.989.2/0.365.9mmHg. These differences were more prominent by -3.38.3/-0.175.7 in female compared to -0.577.4/0.946.0 in male (both p<0.01). Each prevalence of CH, WCH, MH, and UH was 40, 23, 10 and 27%. BP difference between nurse and physician was significantly related with systolic WCE (r2=0.138) and diastolic WCE (r2=0.107). By multivariate regression analysis, these BP difference at clinic was independently related negatively with systolic WCE ( -0.47, p<0.001) and positively with diastolic WCE ( 0.15, p<0.001) and particularly in women ( -0.16, p<0.001). CONCLUSIONS: Our findings indicate that BP difference between nurse and physician may predict the white coat effect, particularly in women, which may help guide hypertensive patients in a better.