Object. In this retrospective study conducted at Atkinson Morley's Hospital and Middlesbrough General Hospital, the authors analyzed 100 matched patients who had suffered subarachnoid hemorrhage (SAH) to determine whether the technical procedure by which aneurysms are treated affects the development of chronic hydrocephalus.Methods. Four hundred seventy-five patients presented with SAH between 1995 and 1998. Exclusion criteria included posterior circulation aneurysms, multiple aneurysms, electively clipped or embolized aneurysms, angiographically undetected SAH, patients who died within 1 month of neurosurgical intervention, and patients with the same aneurysm location but a different Fisher grade.The authors matched 50 patients who underwent embolization of their aneurysms with another 50 who had similar Fisher grades and aneurysm types and underwent clipping of their aneurysms. The maximum incidence of ruptured aneurysms occurred in patients who were between 41 and 60 years of age, with women preponderant in both study groups. In each group, 27 patients had anterior communicating artery aneurysm, 13 had posterior communicating artery aneurysm, seven had middle cerebral artery aneurysm, and three had internal carotid artery aneurysm. The lesions in three patients in each group were Fisher Grade I, in 23 patients they were Fisher Grade II, in 14 they were Fisher Grade III, and 10 patients had Fisher Grade IV SAH. Nine patients among those with clipped aneurysms and eight of the patients who underwent embolization had hydrocephalus for which they needed intervention. These interventions included lumbar puncture, ventricular drainage, and ventriculoperitoneal (VP) shunt placement; three patients in each group needed VP shunt placement.Conclusions. The technical procedure used to treat aneurysms, whether clipping or embolization, does not significantly affect the development of chronic hydrocephalus. However, a larger sample of patients is needed for accurate comparisons and stronger conclusions.