In the early nineties, 40 years after the introduction of iodine prophylaxis in Croatia (10 mg KI/kg salt), a nationwide study was initiated with the aim to determine the real prevalence of goiter in the country. A total of 2436 schoolchildren of both sexes, aged 7-15 years, were included in the study. Investigations were designed in a way to cover most of geographical regions in Croatia and subjects were randomly selected. The prevalence of goiter in schoolchildren was assessed by palpation and in part by ultrasonography of the neck. At the same time urinary iodine excretion was measured and potassium iodide content in salt samples was determined. The results revealed the persistence of mild endemic goiter in the inland parts of Croatia with the prevalence of 6-29% in the age group 7-11 years and 10-43% among the age group 12-15 years. The overall goiter prevalence in schoolchildren in Croatia fluctuates from 8% to 35%. The urinary iodine excretion in Zagreb varied from 1.6 to 24.4 micrograms/dL with a median of 9.0, while in 14% it was below 5 micrograms/dL. The urinary iodine excretion in Samobor varied between 0.5 and 19 micrograms/dL with a median of 7.4 micrograms/dL, while in 30% it was below 5 micrograms/dL. Examination of salt from all three salt plants in Croatia showed iodine contents between 0.0 and 12.73 mg/kg with the average value of 5.39 mg/kg. Such prevalence, most probably due to less than optimum iodine intake, is unlikely to change until potassium iodide content of salt is increased from its present level of 10 mg of KI per kg of salt, with concomitant stricter observance of legal regulations.