BACKGROUND: The aim of this study was to compare the risk conferred by white-coat versus sustained mild hypertension for the development of cardiovascular disease. METHODS AND RESULTS: Patients (n=479) who underwent 24-hour intra-arterial ambulatory blood pressure monitoring on the basis of a persistently elevated clinic systolic blood pressure of 140 to 180 mm Hg were followed up for the development of subsequent cardiovascular events during a 9.1+/-4. 2-year period. White-coat hypertension, defined as a clinic systolic blood pressure of 140 to 180 mm Hg associated with a 24-hour ambulatory systolic blood pressure <140 mm Hg and diastolic blood pressure <90 mm Hg, was present in 126 patients, and the remainder had sustained mild hypertension. A subgroup of patients without complications underwent follow-up echocardiography and carotid ultrasound. White-coat hypertensives were younger (44+/-12 versus 52+/-10 years, respectively; P<0.001) and had a significantly lower incidence of cardiovascular events (1.32 versus 2.56 events per 100 patient-years, respectively; P<0.001) than sustained hypertensives. Multivariate analysis revealed age (P=0.002), sex (P=0.007), race (P=0.001), smoking (P=0.005), and the presence of white-coat hypertension (hazard ratio, 0.29; 95% CI, 0.09 to 0.90; P=0.04) to be independent predictors of subsequent cardiovascular events. Subgroup analysis in patients without complications revealed a lower incidence of left ventricular hypertrophy and lesser degrees of carotid hypertrophy in the white-coat group. CONCLUSIONS: These findings indicate a relatively benign outcome in white-coat hypertension compared with sustained mild hypertension.