BACKGROUND AND OBJECTIVES: Preservation of facial nerve function in vestibular schwannoma (VS) surgery is still a significant operative challenge. Several prognostic factors correlate with postoperative facial nerve function. Most partial facial nerve damage can recover completely without functional defect. However, recovery of the facial nerve in some patients is either incomplete or non-existent. To evaluate the cause of incomplete facial function recovery at long term follow-up (> or =1 year), we analyzed the factors that influenced facial function recovery in a consecutive series of patients that had immediate post-operative, partial paralysis after VS surgery with preservation of neural integrity. MATERIALS AND METHODS: We conducted a retrospective review of 143 cases of VS surgery that occurred between January 1994 and December 2008. Twenty-seven patients that had immediate, postoperative partial facial paralysis and normal preoperative facial function with intact nerve after tumor excision were analyzed with regards to age, sex, tumor size, tumor location, internal auditory canal (IAC) widening, duration of surgical procedure, postoperative complication, and facial function after a postoperative follow-up period of > or =1 year by the House-Brackmann (HB) grading system. RESULTS: Of the 143 patients that underwent VS surgery, 27 (18.8%) patients had immediate, postoperative partial facial paralysis. At long-term follow-up, there were 11 (7.6%) patients with incomplete facial recovery. Facial function recovery after facial nerve injury did not show a significant difference in tumor size, surgical approach, or tumor location. However, preoperative IAC widening and the duration of the procedure were related to facial restoration after surgery. CONCLUSIONS: The injured facial nerve during VS surgery showed incomplete recovery in many cases. Chronic compression of the facial nerve, together with IAC widening preoperatively, led to incomplete restoration of injured facial nerves.