Objectives: To investigate the changes in hearing and to determine factors predicting hearing deterioration in patients with vestibular schwannoma (VS) who undergo gamma knife radiosurgery (GKRS). Design: A retrospective review of medical records in patients diagnosed with VS and initially treated with GKRS at a tertiary care medical center between 1995 and 2015 was performed. Tumor factors (location, volume), parameters related to irradiation to the tumor and cochlea, and distance between the tumor and cochlea were reviewed. Results: Fifty-six patients were included in the final analysis with a mean observation period following GKRS as 24.4 ± 27.8 months. Prior to GKRS, the average pure tone threshold at 500, 1k, 2k, and 4k Hz (PTA4) was 51.0 ± 29.7 dB HL. After GKRS, the mean PTA4 was 71.6 ± 33.3 dB HL. Significant independent odds ratios for hearing deterioration were 8.5 for extracanalicular tumors, 18.8 for more than 10 shots in GKRS, and 12.2 for a distance between the tumor center and cochlea modiolus less than 20 mm. Conclusions: A significant hearing deterioration was shown in 2 years after GKRS. Tumor location, number of radiation shots, and distance between the tumor and cochlea affected hearing level after GKRS.