This study gives quantitative information regarding the effect of brain infarction on the regulation of the cardiovascular system. Electrocardiograms of 16 patients, ranging from 54 to 85 years old, admitted for rehabilitation after an ischemic supratentorial stroke, all without a history of cardiac disease or rhythm disturbances, were recorded during physiotherapy effort. All patients were evaluated for the functional independence measure (FIM) score 48 to 72 hours following admission and repeated at one week before discharge. The heart rate variability (HRV) parameters: standard deviation (SD) of the RR series, the power spectrum of the RR intervals for the low frequency range (LF: 0.04-0.15 Hz), and the high frequency range (HF: 0.15-0.4 Hz) were calculated. The results showed that all heart rate variability parameters had statistically significant relationship with the FIM on admission and discharge scores. In conclusion, the HRV parameters correlate with the clinical measures of function: the greater the HRV parameter the higher the FIM score. The presented technique may prove useful as a prognostic tool providing a simple way for determining functional performance of stroke patients.