Continuous drainage of lumbar cerebrospinal fluid (CSF) was analyzed for the preoperative management of patients with aneurysmal subarachnoid hemorrhage (SAH) in 50 consecutive cases of surgically treated aneurysmal SAH. Patients were divided into a lumbar drainage group, in whom continuous lumbar CSF drainage was established for preoperative management, and a non-lumbar drainage group. Rebleeding from the aneurysm during the insertion of the lumbar drainage tube and during continuous lumbar drainage, effect on the control of the systolic blood pressure, and effect on the sedation of the patient were examined. Continuous lumbar CSF drainage significantly decreased the systolic blood pressure. Seven of 17 patients in the non-lumbar drainage group had systolic blood pressure uncontrollable to below 150 mmHg even when a large amount of nicardipine was used, whereas only two of 33 patients had the same problem in the lumbar drainage group. Sedation was better in the patients in the lumbar drainage group with a smaller amount of analgesics. The rebleeding rate was 11.7% among patients in the non-lumbar drainage group, and 9.09% among patients in the lumbar drainage group. No rebleeding occurred during insertion of the lumbar drainage catheter. Continuous lumbar CSF drainage improved control of systolic pressure and sedation, and is a useful method of preoperative management for patients with aneurysmal SAH.