We retrospectively examined the effect of Cepharanthin to prevent radiation xerostomia in 37 cases of head and neck cancer. In the Cepharanthin group, the degree of xerostomia was milder than in the non-Cepharanthin group in spite of higher normal tissue complication probability (NTCP) and mean dose (MD) of parotid glands. In the non-Cepharanthin group, the degree of xerostomia was significantly correlated with NTCP and MD of parotid glands. MD of parotid glands and use of Cepharanthin were significantly related to more severe xerostomia by multivariate analysis with logistic regression. Cepharanthin may prevent radiation xerostomia after radiotherapy for head and neck cancer.