OBJECTIVE: Hydrocephalus and vasospasm are the common complications of aneurysmal subarachnoid hemorrhage (SAH). In spite of development of perioperative management and operative technique, hydrocephalus and vasospasm are the causes of the neurological deficit and poor prognosis. This study was designed to investigate whether the frequency of a shunt-dependent hydrocephalus in patient suffering from aneurysmal subarachnoid hemorrhage and delayed cerebral ischemia can be related to the duration and amount of cerebrospinal fluid drainage and medical history. METHODS: Retrospective analysis of consecutive 96 patients with aneurysmal subarachnoid hemorrhage was made from January 2000 to December 2002. Eighty one of these patients underwent the procedure for CSF drainage and 15 patients did not. 81 patients with aneurysmal SAH were divided into two groups which underwent shunt procedure and did not. In these two groups, we investigated and compared the incidence of shunt-dependent hydrocephalus and ischemia according to age, sex, aneurysmal site, H-H grade, Fisher grade, medical history and the amout of CSF drainage. RESULTS: The incidence of hydrocephalus following SAH was 53.1% and shunt-dependent hydrocephalus was 16.7% in 96 patients. The duration, total volume, and daily volume of CSF drainage were 6.9+/-3.3 days, 1542.3+/-982.5 ml, and 211.5+/-49.2 ml, respectively. The relationship between the daily volume of CSF drainage and shunt-dependent hydrocephalus was determined to to be statistically significant (p<0.05). Cerebral infarction and shunt-dependent hydrocephalus were found to be statistically associated (p<0.05). CONCLUSION: The continous drainage of cerebrospinal fluid in patients of aneurysmal subarachnoid hemorrhage increase chance of delayed hydrocephalus and they have not shown decrease cerebral infarction as a result of vasospasm.