To test whether cerebral autoregulation is impaired in patients with postural tachycardia syndrome (POTS) we evaluated 17 healthy control subjects and 27 patients with POTS. Blood pressure (BP), heart rate, and cerebral blood velocity (CBV) (transcranial Doppler) were recorded at rest and during 80° head-up tilt (HUT). Static cerebral autoregulation as assessed from the change in cerebrovascular resistance during HUT was the same in POTS and in controls. The properties of dynamic cerebral autoregulation were inferred from transfer gain, coherence and phase of the relationship between BP and CBV estimated from filtered data segments (0.02-0.8Hz). Dynamic cerebral autoregulation of patients with POTS did not differ from that of controls. The patients' dynamic cerebral autoregulation did not change over the course of HUT despite increased tachycardia suggestive of worsening orthostatic stress. Inflation of MAST pants substantially reduced the tachycardia of patients with POTS without affecting cerebral autoregulation. Symptoms of orthostatic intolerance were reduced in half the patients following MAST pants inflation. We conclude that cerebral perfusion and autoregulation in many patients with POTS does not differ from that of normal control subjects.