A cross-sectional descriptive study was conducted on Iodine Deficiency Disorders and its determinants among 177 school children aged 8-12 years in Chiangmai Province of Thailand during February 2000, with the aim to identify the prevalence rate of goiter among school children and its determinants. The total goiter rate was 10.7 percent. The average age of children was 10.5(+,ฑ)1.4 years. The prevalence rate of goiter was almost equal among male and femal (11.2% and 10.2% respectively). In the study group the average age of respondents parents was 38.1(+,ฑ)9.3 years, fathers out numbered mothers by 16.4%. The average monthly family imcome was 3,139(+,ฑ)3,139 Baht. The main occupation of both was in agriculture. The majority of people were aware of IDD. The respondents parents had poor knowledge, but there was no association between knowledge and prevalence of goiter. The family practices in cooking and storage of salt including seafood was satisfactory. In the study area, most salt used (85.2%) was not iodized and the level of iodine content in the salt used in the community was very low (< 15 ppm). The large number of salt types being used in the community was crystalline, while very low percentage of families consumed powdered salt. At traders level, the majority of salt being sold was not iodized. According to the school and health authorities information, education, and communication system, there was proper and systematic channels of communication. Health personnel were imparting health education to the students and to the community at large. However the IDD still remains to be a major public health concern in Chiangmai province, although it has been significantly reduced. Trgarding the available data, the basic problem was the lack of iodized salt in the market especially in the study area. The proper information, education, and communication is required in order to eliminate the IDD from the study area.