A higher incidence of nodular goitre and less differentiated types of thyroid carcinoma have been observed in iodine deficient regions. North-Eastern Poland was an area with a moderate deficiency of iodine until the introduction of the mandatory salt iodination in 1997 (30±10 mg KJ/kg NaCl). The aim of our study was to compare the incidence of goitre, thyroid carcinoma and urine excretion of iodine in the inhabitants of the North-Eastern Region of Poland in 1997 and 2005. In 1997 816 persons were investigated, 431 (52.8%) of whom reported for follow-up investigation in 2005. The study consisted of a questionnaire. thyroid ultrasonography and the measurement of iodine concentration in random urine sample. Parenchymatous goitre was found in 267 persons (32.7%) in 1997 and in 37 persons (8.6%) in 2005 (P<0.001. chi2-58.165). The incidence of nodular goitre was 12.75% (104 persons) and 24.59% (106 persons), respectively (P<0.001. chi2-19.557). In 1997 three cases of papillary carcinoma were diagnosed. and in 2005 1 case. Decreased iodine excretion was observed in 71.28% subjects in 1997 and in 19.1% in 2005 (P<0.001. chi2-105.748). Conclusion. During the last 8 years, the incidence of parenchymatous goitre in the NorthEastern Poland significantly decreased, whereas the percentage of nodular goitre increased in the period analysed. Prospective analysis did not reveal an increase in thyroid carcinoma incidence. The observed changes may be due to the introduction of the mandatory iodination of table salt in Poland in 1997.