Cerebral perfusion pressure (CPP) is elevated in preeclampsia, and may predispose to cerebrovascular complications and progression to eclampsia. We estimated zero flow pressure (ZFP) and CPP using simultaneously obtained arterial blood pressure and middle cerebral artery blood flow velocity in 10 women with preeclampsia, all treated with methyldopa with or without nifedipine, and 18 healthy pregnant controls. Mean +/- SD ZFP was lower in women with preeclampsia than in controls (16.8 +/- 10.9 vs. 31.7 +/- 15.0mmHg, p=0.01) whereas CPP was considerably higher (82.3 +/- 17.7 vs. 55.0 +/- 11.7mmHg, p<0.001), as was the cerebral flow index (41.9 +/- 18.0 vs. 25.6 +/- 11.2, p=0.02). There was a significant correlation between blood pressure and CPP in women with preeclampsia, but not in controls. Women with preeclampsia may have an increased cerebral perfusion due to a reduced ZFP and increased CPP despite treatment with antihypertensive medication. More rigorous antihypertensive therapy, aimed at reducing CPP, could result in a decrease in cerebral complications in women with preeclampsia.