OBJECTIVE: The purpose of this study was to determine the clinical significance of intraventricular hemorrhage (IVH) in patients with ruptured aneurysms. METHODS: Of 1034 patients who were admitted to our hospital with ruptured aneurysms between 1994 and 2007, 128 (12.4%) had IVHs. The clinical, radiologic characteristics, and surgical outcomes in the IVH group were compared with the no-IVH group. RESULTS: The IVH group had a shorter time interval to admission. The incidence of IVH was significantly higher in patients > 70 years of age (p=0.021), males (p=0.000), alcohol abusers (p=0.039), patients with a Glagow Coma Scale (GCS) < or =8 (p=0.000), and patients with a Hunt and Hess grade of 4-5 (p=0.000). IVH was more common in patients with ruptured posterior circulation aneurysms (p=0.000) and anterior communicating artery aneurysms (p=0.036). The incidence of thick, diffuse subarachnoid hemorrhage (SAH; p=0.004), intracerebral hemorrhage (ICH) >10 cc (p=0.006), rebleeding (p=0.010), and shunt-dependant hydrocephalus (p=0.000) was significantly higher in the IVH group than the no-IVH group. The mortality rate in the IVH group was significantly higher than the no-IVH group (48.4% versus 22.1%). The amount of IVH had an influence on the mortality; IVH involving all of the ventricles (59.7%) and IVH only involving some of the ventricles (33.9%) was associated with a 6.6- and 2.3-fold higher mortality than the no-IVH group, respectively. IVH was significantly associated with a poor surgical outcome; however, this association was not significant in patients with a GCS < or =8, or histories of rebleeding or seizures. CONCLUSIONS: In patients with ruptured aneurysms, IVH reflects the clinical severity of SAH. IVH has a negative influence on surgical outcome, except in patients with a poor clinical status pre-operatively.