DEFINITION AND PREVALENCE OF WHITE-COAT HYPERTENSION: White-coat hypertension describes the phenomenon of an abnormal blood pressure reading when taken by a physician and a normal reading with ambulatory or home monitoring. The results of studies suggest that the true prevalence of white-coat hypertension may be 20%. The magnitude of the effect using either the oscillometric or the auscultatory method of measurement appears to be comparable. PROGNOSTIC SIGNIFICANCE: The prognostic significance of the white-coat effect is not established, and prospective trials are needed to assess the risk. At present, because of the unpredictability and unreliability of this effect, we recommend that patients with white-coat hypertension should not be included in trials on the efficacy of antihypertensive drugs.