To assess possible changes in blood pressure and heart rate associated with panic attacks, we performed automatic ambulatory blood pressure monitoring in 12 newly diagnosed, drug-free, and normotensive (casual blood pressure, less than 140/90 mm Hg) medical patients recently diagnosed with panic disorder. Detailed journals were designed for the study to assess the timing and symptoms of the panic attacks and the levels of activity. Systolic blood pressure increased by 27 +/- 9 mm Hg during the hour of the panic attack compared with the hour immediately prior to the episode of anxiety, while diastolic blood pressure increased by 5 +/- 2 mm Hg. The ambulatory heart rate increased by 14 +/- 6 beats per minute during the hour of panic attack vs the hour immediately prior to the attack. There was a strong relationship between the increase in heart rate and increase in systolic blood pressure. These data confirm that normotensive patients with panic disorder have episodically hypertensive blood pressure readings associated with an increase in heart rate; these hemodynamic alterations appear to be secondary to their panic attacks and not to increased physical activity. However, despite these episodic "hypertensive" periods, the mean ambulatory blood pressures remain within the normotensive range.