We investigated the effect of prostaglandin E1 (PGE1)--induced hypotension during sevoflurane anesthesia on the cerebral blood flow (CBF), autoregulation and internal jugular venous O2 tension (PjO2) in 8 patients undergoing neurosurgery. Although the mean arterial pressure decreased from 95.3 +/- 3.8 mmHg (mean +/- SD) to 63.6 +/- 8.0 mmHg by continuous intravenous infusion of PGE1, CBF did not change significantly (97.2 +/- 10.6% of control value). During hypotensive anesthesia, autoregulation was well maintained in all patients, and the values of PjO2 did not suggest brain hypoxia at all. The results indicate that hypotensive anesthesia induced by PGE1 and sevoflurane is a safe and a reliable method for neuroanesthesia.