['The aim of this study was to test the hypothesis that blood pressure (BP) reactivity to the stress of a clinic visit, the so-called white-coat effect, is associated with increased BP reactivity to physical activity.', 'Patients referred to our clinic for assessment of hypertension prospectively underwent 24-h ambulatory BP monitoring and simultaneous actigraphy.', 'The difference between mean clinic BP and mean daytime ambulatory BP was considered to be a measure of the white-coat effect. Presence or absence of a white-coat effect (clinic-daytime difference > 0 mmHg) was added to a mixed model regression of BP on mean activity score for the 10-min interval preceding BP measurement.', 'The group (n = 421) was heterogeneous in age, gender, mean 24-h BP and use of antihypertensive medications. A total of 259 patients had a systolic white-coat effect; for diastolic BP there were 264. Female patients exhibited a significantly larger white-coat effect. Coefficients for the regressions of both systolic and diastolic blood pressure on physical activity levels were significantly higher in those who had a white-coat effect.'] Is the white-coat effect associated with increased blood pressure reactivity to physical activity?