Cerebrovascular dysautoregulation is well recognised following acute stroke, and thus blood pressure (BP) changes may have important effects on cerebral blood flow. Whilst absolute BP levels have been shown to influence outcome in some studies, the importance of short-term BP variability has not been addressed. We assessed beat-to-beat BP and pulse interval variability non-invasively using the Finapres device in 32 patients with CT-diagnosed acute cerebral infarction compared to a control group matched with respect to age and sex. Systolic BP variability was assessed as the standard deviation (SD) of all measurements and as the root mean squared of successive differences (RMS; which removes the portion of variability related to the underlying BP level). Systolic BP variability (taken as either the SD or the RMS) was significantly greater in acute stroke patients than controls. This difference is unlikely to reflect impaired cardiac baroreceptor sensitivity in acute stroke patients as no differences were observed in pulse interval variability compared to controls, but may be related to alterations in peripheral vascular resistance mediated by centrally induced changes in sympathetic nervous system activity. The prognostic significance of increased BP variability and the implications for BP management in acute stroke require further evaluation.