The article presents results of study of the impact of iodine deficiency and technogenic fluoride on the state of the thyroid gland in children. On the example of two districts of the city of Bratsk there were executed dynamic investigations (2002 and 2012), including the estimation of the pollution of ambient air and soil by fluorine compounds, levels of iodine intake by the body, the clinical examination of children aged from 5 to 7 years d and interviewing of their parents. In the course of the medical examination there were executed: physical examination by the pediatrician, endocrinologist, ultrasound examination of the thyroid gland, the determination both of serum hormone content by radioimmunoassay and urinary excretion offluorine and iodine. Concentrations of hydrogen fluoride and a solidfluorides in ambient air led to the accumulation offluoride ion in the soil. The iodine entering with drinking water and food, was established to provide only 37.5-50% of the daily requirement of iodine. Increased fluoride ion content in urine and milk teeth in children is associated with the concentrations of the fluorine-containing pollutants in the ambient air and soil. The fluoride pollution against the background of the natural iodine deficiency was established to increase the frequency of functional and morphological disorders of the thyroid gland in children.