The predictive value of intraoperative stimulation thresholds for facial nerve function, using a constant current system was examined in 49 patients undergoing resection of cerebellopontine angle tumors. Immediately postoperatively, 75% of the 0.1 mA threshold group, 42% of the 0.2 mA group and 18% of the >= 0.3 mA group had good (Grade I or II) facial nerve function. One year postoperatively, 90% of the 0.1 mA group, 58% of the 0.2 mA group and 41% of the >= 0.3 mA group had Grade I or II function. A statistically significant breakpoint of 0.2 mA was found to predict good postoperative facial function. Delayed facial paralysis occurred in 22% of patients, but carried a favorable prognosis. Both current stimulation threshold and duration are necessary for a meaningful comparison of data between investigators.