not diagnosed as hypertensives, i.e. the number of Definition of white coat/office hypertension undetected cases is still relatively high; on the other, a large number of people whose blood pressure shows a The first reports on the ‘white coat effect’ were pubtransient rise only in the physicians office or the clinic lished over 250 years ago [1]. In 1738, Christoph (office hypertension), but who do not have established Hellwig reported on ‘pronounced changes’ in the hypertension are incorrectly classed as hypertensives patient’s pulse ‘on appearance of the doctor’ [2]. He, [4–7]. When ABPM is used to diagnose office hypertentherefore, recommended the doctor to sit down and to sion, the prevalence is approximately 20–30%. The talk to the patient for a while before studying the prevalence differs markedly depending on the cutoff quality of the pulse once or several times, a recompoints for defining the upper range of normal ambulatmendation reflecting our modern guidelines. Shortly ory blood pressure values. after, in 1756, Theophile de Bordeu wrote ‘In order to The epidemiological dimension is huge i.e. approxiestimate the quality of the pulse it is necessary to feel mately 3 million people with office hypertension in the pulse several times; it is an exception that the Germany alone [6 ]. Therefore, three main questions presence of the doctor does not lead occasionally to arise: some changes which may elevate or increase it: the practitioners never forget to keep in mind the pulse (i) Is it an innocent blood pressure variant without which they call the pulse of the doctor’ [3]. any cardiovascular risk? Differentiation between occasionally high blood (ii) Will the affected subjects develop established pressure under certain circumstances (e.g. in the dochypertension? tors office or in the clinic) and established hypertension (iii) What is the pathophysiology? Does office hyperis difficult. Even repeated blood pressure readings on tension represent only an abnormal blood presdifferent occasions in the office or clinic cannot solve sure reaction during the measurement in the office this problem. Ambulatory blood pressure measurement or clinic or is it characterized by some other (ABPM) away from the physician’s office/clinic is the abnormalities, i.e. humoral, functional and strucideal method to identify patients with office hypertentural alterations which may lead to established sion overnight. White coat or office hypertension is hypertension? characterized by an persistent blood pressure increase during conventional measurement in the doctors office