The Province of Salta, located in the northwest of Argentina, showed severe endemic goiter-cretinism. The purpose of our work, therefore, was to evaluate the results of the iodized salt prophylaxis measure implemented since 1963. In 1980-1981 the prevalence of goiter was determined in 16,935 school children whose ages ranged from four to 15 years. The urinary iodine/creatinine index was also determined in a subsample of 401 children. Findings revealed that the goiter prevalence in the Province was 16.1%. In 10 Departments of the Province, those with greater socioeconomic development and denser population, the prevalences found were below 10%, limit established as endemic. In the remaining 13 Departments, especially in those less developed--where mountainous regions make their access difficult and hence, their populations consume non-iodized salt obtained from natural salt basins--values exceeded this limit. The average ioduria was 104.0 micrograms I/g Cr, with 4.5% presenting values below 25 micrograms. After 20 years of prophylaxis, endemic goiter has therefore been partially eradicated. It is suggested, however, that consumption of iodized salt and, even the supply of iodized oil in those areas where prevalence is high, be recommended.