Management of blood pressure (BP) abnormalities in patients with autonomic failure is usually based on office BP readings. It is uncertain, whether office readings reflect actual BPs during a typical day. Therefore, in 45 patients with autonomic failure, we compared office BP values during a tilt test with those captured on a 24-h ambulatory monitor. Office BP values while supine predicted well the level of nighttime hypertension. However, in only 33 % of patients, office values during tilt test accurately reflected hypotension during a typical day. Therefore, ambulatory monitoring is useful to gauge the true severity of hypotension in patients with autonomic failure.