The management of hydrocephalus in association with a cerebellopontine angle tumor is controversial. There is a widely held belief that initial therapy should always be directed toward treatment of hydrocephalus before definitive surgery. The potential problems of cerebrospinal fluid (CSF) shunting and drainage have to led to an evolution in the management of hydrocephalus at St. Vincent's Hospital. There is growing evidence that complete removal of cerebellopontine angle tumors will result in resolution of hydrocephalus without requiring other methods of CSF decompression. The authors present their experience of 14 patients with hydrocephalus found in a recent series of 104 consecutive cases of acoustic neuroma. This study has detected a significant correlation between hydrocephalus and increasing tumor size (P = .0234). The mean tumor size in this series was 3.8 cm. The series has also demonstrated that successful. safe, and complete tumor removal can be achieved without CSF drainage before surgery.