Simple goiter is one of the most prevalent endocrine disease all over the world. Before iodine supplementation in 1990, Khuzestan province was an endemic area for goiter in Iran. This study was performed in 2002-2003, about 13 years after iodine suplementation, to determine the prevalence of goiter and urinary iodine excretion among 1800 school children (6-10 years old) in Ahwaz. The subjects were chosen by cluster sampling. Physical examination and goiter staging according to WHO criteria was done by 4 medicals student trained in endocrinology department. A questionnaire included: age, sex and level of iodized salt consumption, was filled out for each person. Urinary iodine excretion (by digestion method), was assessed in 75 person by random sampling. In addition, thyroid function tests which included: T3, T4, T3RU by RIA and TSH and serum ferritin by IRMA method were assessed randomly in this selected population. The results showed that 52.5% of the subjects were males and 47.5 were females. 712 school children (39.6%) had goiter (17.3% stage la, 18.4% Ib, 3.7% stage H). There was no case of stage HI goiter. Prevalence was higher in girls (43.5% versus 35.9%) (P<0.01). 90.4 % of study group consumed iodized salts. The mean urinary iodine excretion was 31µg/dl in normal children, 26µg/dl in person with stage la goiter, 21µg/dl in Ib goiter and 14µg/dl in stage H goiter. Urinary iodine was significantly higher in normal children than those with goiters stage Ib or H. 9.3% of studied persons had urinary iodine excretion lower than 10µg/dl, 18.7% between 10 20µg/dl and 72% had urinary iodine more than 20µg/dl. The mean T4, T3, T3ru and TSH in normal and goiterous persons were 7.7 versus 8.02µg/dl, 184 versus 186ng/ml, 32% versus 33% and 2.5 versus 3.4miulml respectively. Only TSH showed significant difference between normal and goiterous persons (P<0.01). There was no significant difference in the mean serum ferritin concentration between normal and goiterous children (29 versus 23µg/dl). These findings suggest that after 13 years of consumption of iodized salt, more than 90% of studied persons had urinary iodine excretion more than l0µg/dl, and goiter still has a high prevalence of 39.6%, therefore, other goitrogen factors should be sought for in this area.