The objective of this study was to evaluate the results of endoscope-assisted acoustic neuroma surgery in posterior fossa approach. Between 1996 and 2002, 60 consecutive patients with acoustic neuroma were operated via the retrosigmoid suboccipital approach. Standard 4-mm sinus endoscopes at different angles were used during the surgeries either for inspection or tumor endoscopic dissection. Clinical parameters and treatment outcome were evaluated retrospectively. Tumor sizes were small, medium and large in 46.6, 45 and 8.3% of the patients, respectively. The hearing preservation rate, which did not correlate with tumor size (p > 0.05), was 24.4%. The need for facial reanimation surgery, which was needed in 5% of patients, was significantly higher in the large tumors than in the small and medium tumors (p < 0.001). Cerebrospinal fluid fistula rate, which was not related to tumor size (p > 0.05), was 13.3%. Tumor recurrence or residual tumor was not encountered at all. In conclusion, endoscopes give accurate information about the relationship between the tumor and the adjacent structures and help control the fundus of the internal auditory canal to ensure complete tumor removal. It is also helpful in visually verifying the continuity of the facial and cochlear nerves. The use of endoscopes does not appear to increase the hearing preservation rate, but is very helpful in complete tumor removal in the posterior fossa approach. Copyright (C) 2005 S. Karger AG, Basel.