Abstract: Objective To explore the factors affecting the thy roid health of Buddhist monks and nuns living in Putuo Mounta in.Methods The subjects were asked to fill in a questionnaire on thyroid health and to receive aphysical examination with a B modeultrasonic thyroid scan.The levels of serum triodo thyronine(TT₃),thy roxine(TT₄),thyroid stmiulating horm one(TSH)and urinary iodine were also examined.Results A total of 294 Buddhists were investig ated.Ninety three (31.6%)subjects were found with variousultra sonic abnormalities including 49(16.7%)cases of nodes,35(11.9%) cases of cysts,and 9(3.0%)cases of thy roid enlargement.The median of urineiod ine(NUI)for the subjects was 271.7 μg/L.The ultrasonic abnormality ratio of Buddhists who were old than 50 years or residing in Putuo Mounta in fro more than 8 years was significantly higher than that of others(χ²=17.27,P<0.01;χ²=8 14,P<0.05,respectively).But the urinary iodine level of Buddhists with ultrasonic thyroid abnormality had no significant difference from others (P>0.05).Conclusion There may be some environmental factors affecting the thyroid health of the Buddists in Putuo Mountain.Physical examination should be conducted among the Buddhists to diagnose thyroid diseases early.