The effects of iodized and non-iodized salt on the thyroid gland and its hormones T3, T4 and thyroid stimulating hormone (TSH) were studied in 200 individuals who were the residents of plain areas of greater Mymensingh district. The subjects were collected from the Center for Nuclear Medicine and Ultrasound, Mymensingh. Out of 200 individuals 150 were using iodized salt and 50 were using non-iodized salt. The iodized and non-iodized salt users were marked as study and control groups respectively. Blood samples were taken from both the groups and T3 and T4 in blood serum were determined by radioimmunoassay (RIA) while TSH was determined by immunoradiometricassay (IRMA). The mean concentration of T3 were 2.633 nmol/L and 2.223 nmol/L and T4 concentration were 122.444 nmol/L and 110.355 nmol/L in study and control group respectively. The mean TSH concentration was 5.044 mIU/L and 9.622 mIU/L in study and control group respectively. The data indicated that continuous and long term use of iodized salt increased both T3 and T4 and decreased TSH in study group. The results were significant (p<0.05) when compared to that of the control. The results suggested that mandatory mass consumption of iodized table salt without T3, T4 and TSH screening of blood may produce iodinated salt induced thyrotoxicosis (ISIT) in peoples living in plain areas of Bangladesh. We suggest close regular monitoring of T3, T4 and TSH and urinary excretion of iodine of individuals who are using iodized salt for better management of iodinated salt program in our setting.