The aim of the study was to evaluate the frequency of needed shunt surgeries in 514 patients who underwent surgery for a ruptured intracranial aneurysms. The patients were consisted of 207 patients who were treated from 1986 to 1988(historical control group) and 307 patients treated from 1994 to 1996(study group). In the study group, an earlier aneurysm surgery and more frequent use of adjunctive procedures applied(lumbar and cisternal drainage, and opening of the lamina terminalis and the Liliequist membrane) compared to the control group(p<0.005). Twent-one patients(6.8%) required shunt operations in the study group, while it was necessary in 32 patients(15.5%) of the control group(p<0.005). However, occurrence of a hydrocephalus in both groups were similar. It is concluded that the frequency of a shunt operation has been decreased in the study group presumably due to an earlier surgical intervention, and an aggressive drainage of the bloody cerebrospinal fluid from the cisterns and the ventricles during or after an aneurysm surgery.