Introduction: Since the implementation of the Iodized Salt National Law the percentage of goiter in San Juan’s State diminished from 30 to 16%. In July of 2000 a report was carried out in the school-children from the towns of «Punta del Médano» and «Colonia Fiscal», located at 50 kms from San Juan’s city, and around 10% of palpagoiter was detected. The average of the urinary iodine excretion in these children was inside the normal range, although it was near the inferior limit (Punta de Médano: 107±45 and Colonia Fiscal: 120±25 mcg/l). We wonder if this light endemia of goiter is related to the lack of a strict execution of the legislation, or if there are another factors that contribute with its pathogeny. This situation motivated us to reevaluate these children and to search for the objectives that we mention h ereunder. O b j e c t i v e s : 1 – To evaluate what percentage of goiter is related to antimicrosomal antibodies. 2 – To detect h y p o t h y roidism in children with goiter. 3 – To study other causes of goiter’s endemia, besides the deficit of i odine. 4 – To value how the presence of goiter influences children’s growth and development. Materials and Methods: The 21 children with goiter from «Colonia Fiscal» and the 19 same ones from «Punta del Médano», were convoked to the school, accompanied by their parents. We made the thyroid palpation and m e a s u red height and weight of each children with their corresponding percentiles. The parents were interro g a t e d about the personal and family history of thyroid pathology and autoimmune illnesses. A nutritional interview was carried out to value the ingestion of goitrogen substances, and the toxic habits. We also completed the mensuration of their parent’s height to calculate the children’s objective-genetic size. Each one of the children was taken a blood sample to determinate serum thyrotropin (TSH), thyroxin (T4) and antimicrosomal thyroid antibodies levels. We took as a control group a population of children equivalent in number, sex and age, with normal thyroid palpation. R e s u l t s : In the town of «Colonia Fiscal» the average value of TSH in the children with goiter, was significantly higher than the control group, 2,51 ± 1,43 and 1,62 ± 1,13 μUI/ml respectively, (p = 0,019 Student’s «t» test); same result was obtained for the median with the Mann-Whitney test, (p = 0.0108). The children that consumed well water had a percentage of goiter significantly higher than those who drunk regular water (p=0,02 Chi-square Test). The family background of goiter was significantly bigger in the children with goiter with respect to the controls (47,6% vs. 11%, p=0,021 Chi-Square Test / p=0,24 Fisher’s Exact Test). There were neither differences in the ingestion of goitrogenic foods nor in the antimicrosomal antibodies. The goiter didn’t harm the percentiles of stature, weight and body mass index. In the town of «Punta del Médano», on the contrary, there were not any proven statistical difference in any of the mentioned tests. In only two children, from both towns, the value of TSH was superior to the normal range for the method (6,22 and 5,47 U/ml). The T4 was normal in all the children. Only the 5% of this population had antimicro s omal antibodies and there were not differences among the children with and without goiter. C o n c l u s i o n s : We hereinabove demonstrated that in this population the goiter is not due to the ingest of g o i t rogenic foods neither related to antimicrosomal antibodies. In the town of Colonia Fiscal It would be re l ated to the family background of goiter and the probable presence of goitrogenic substances carried in the well w ater. Considering the iodine urinary levels, we continue wondering if the goiter prevalence