Abstract: Objective To evaluation of the parotid function using dynamic parotid scintigraphy in nasopharyngeal carcinoma patients treated with external beam radiation therapy.Methods Twenty-one nasopharyngeal carcinoma patients were included into this study.Dynamic parotid scintigraphy was performed before and after external beam radiation therapy.Semi-quantitative parameters of parotid (uptake index, excretion rate and excretion index) was used to evaluate the changes of parotid function.Results UI, ER and EI of parotid were decreased markedly after external beam radiation therapy, t is 56.65, 41.34, 30.69 respectively, P<0.001.The uptake and excretion function of the parotid were all impaired, which correlated with the dry mouth symptom of the patients.Conclusion Dynamic parotid scintigraphy can play a key role in the evaluation of parotid function in nasopharyngeal carcinoma patients treated with external beam radiation therapy.