Preoperative dynamic autoregulatory responses in 20 patients considered as candidates for vessel temporal clipping (TC) and/or arterial hypotension (AH) at surgery for aneurysms were studied by the thigh cuff method. Normal autoregulatory responses at a regulation rate (RoR) of 20.4 +/- 2.8%/s were found in 10 patients > 30 days after subarachnoidal hemorrhage (SH) while RoR was 12.5 +/- 2.5%/s in 10 other patients (30 days, grade III WFNS showed autoregulation impairment. TC and/or AH were proceeded in 17 operated patients. One postoperative death was due to pulmonary embolism. Two poor results with persistent neurological disorders at discharge were associated with TC but in 1 patient. This patient had severe vasospasm and the lowest RoR (9%/s). There were no TC and/or AH postoperative complications in other 14 patients. All of them and 3 other patients with direct aneurysm clipping had a fair outcome.