We evaluated the efficacy and safety of stereotactic body radiation therapy (SBRT) for patients with head and neck tumors. From April 2005 through April 2008, 34 patients with head and neck tumors were treated with CyberKnife SBRT. Twenty-one of them had prior radiotherapy. Treatment sites were orbit (n = 7), cervical lymph nodes (n = 6), nasopharynx (n = 5), oropharynx (n = 4) and others (n = 12). The prescribed dose ranged from 19.5 to 42 Gy (median, 30 Gy) in 3-8 fractions for consecutive days. The target volume ranged from 0.7 to 78.1 cm(3) (median, 11.6 cm(3)). The median follow-up was 16 months. Treatment was well tolerated without significant acute complications in any cases. Complete response rate and partial response rate were 32.4% and 38.6%, respectively. The overall survival rates were 70.6% and 58.3% at 12 and 24 months, respectively. The overall survival was better in patients without prior radiotherapy within the previous 24 months or in case of smaller target volume. Six patients suffered severe late complications. All these patients had prior radiotherapy, and 2 of them developed massive hemorrhage in the pharynx and both died of this complication 5 and 28 months, respectively, after SBRT. Our preliminary results suggest that SBRT is an effective treatment modality for head and neck tumors. However, re-irradiation has significant risk of severe and even fatal late complications in the form of necrosis and hemorrhage in re-irradiated areas.