Abstract: ObjectiveTo investigate iodine nutrition and thyroid health of the residends in Zhoushan archipelago and to evaluate the effect of universal salt iodization(USI).MethodsSalt-wokers(consuming non-iodized salt)and farmers (consuming iodized salt)were surveyed with a questionnaire and their thyroid conditions were assayed by B-mode ultrasound.Meanw hile,the urinary iodine concentration and the function of thyroid were measured.ResultsExcluding the iodine intake from iodized salt,the amounts of daily iodine intake were 161.6μg and 137.2μg for the salt-woker and the farmers,and there was no significant difference between the two groups.The median concentration of urinary iodine of the salt-wokers was 116.3μg/L,signicantly lower than that of the farmers(188.9μg/L).The prevalence of thyroid disease had no significant relation to iodine intake,smoking,alcohol drinking,and tea consumption(P>0.05).ConclusionThe residents in Zhoushan archipelago have adequate iodine intake.The key influential factor of the urinary iodine concentration is the intake of iodized salt.The effect of USI in Zhoushan archipelago should be studied.