We compared the cerebrovascular response to various cognitive tasks of cardiovascular patients and healthy controls by using transcranial Doppler ultrasonography (TCD). Cognitive task-induced cerebral blood flow velocity (BFV) changes in 66 candidates for coronary artery bypass graft surgery (mean age 59.4 +/- 7.5) were compared with the functional BFV measurement of 60 healthy controls (mean age 58 +/- 7). Absolute BFV values during baseline and activation were monitored with TCD. Relative increase of the BFV was calculated from the immediately preceding rest period to the following activation. A manova with group (patients versus controls) as between-subjects factor showed no differences in absolute BFV during the rest period. For absolute BFV during activation, a significant difference between the two groups was found. Although for each test the percentage change was smaller in the cardiac group, the difference just failed to reach significance. An explorative multivariate linear regression analysis with the absolute activation and percentage change as dependent variables and coronary risk factors as independent variables revealed no significant predictors. Using functional TCD we found that BFV values during activation were significantly lower in cardiac patients compared with healthy controls. Future research should focus on the possible explanations of this phenomenon.