Abstract: Objective To assess the prevalence of thyroid diseases associated with excessive iodine content in drinking water.Methods Two townships were selected at random.Iodine excess township had a median water iodine concentration of 1284.1μg/L,and the iodine normal township had a median of 77.9μg/L.Thy roid conditions of all residents in two villages were assessed clinically.The prevalence of thyroid diseases was assessed.Results The prevalence of all thyroid diseases was 2.39 times higher in iodine excess tow nship than that in iodine normal township.Higher prevalence was found across age groups in iodine excess township.The prevalence of thyroid diseases was 2.71 times higher among females than males in the iodine excess to wnship,which compared 3.70 times in the iodine normal tow nship.Conclusion Higher prevalence of thyroid diseases found in iodine excess township may be associated with excessive iodine content in drinking water.Necessary measures are needed to reduce population iodine intake.