The well differentiated thyroid cancer patients had a better prognosis. High-dose radioiodine therapy may induce immediate and long-term side effects to patients. The aim of this paper is to investigate the side effects after high-dose radioiodine therapy on thyroid cancer patients and the relation with cumulative therapy dosage. According to the common side effects of 131I therapy

10 questions was chosen to set up a standard questionnaire. Patients were followed up by senior nuclear medicine physicians and the results were analyzed and compared. The results showed that the late symptom of sialadenitis and severe dry mouth were intensively related with cumulative therapy dosage. It is suggested that during the therapy certain necessary means should be adopted to reduce the potential side effects and improve the patients’ life quality.