Résumé : Randomized subjects (n = 294), (35 young children, 6-30 months old - 91 children 8.6 ± 0.7years, 116 teenagers 13.2 ± 1.9y - 52 young women 28.5 ± 6.1 y) leaving in a mountainous area of Reunion Island (Cirque de Salazie) were evaluated according to the following : a questionnaire related to food intake, cervical palpation for thyroid size evaluation and collections of urine and foods (natural and mineral water, breast and commercial milk and salt) for iodine measurement. Neonatal TSH of 308 new borns in Salazie were compared to TSH of 300 new-borns of Lille (France). The prevalence of goiter increases with age (0% in young children, 12.1% in children, 23.3% in teenagers, 38.4% in women) whereas median urinary iodine (μg/dl) decreases in the same groups (12-7.8-5.6-4.2). The intake of milk and dairy products significantly decreases from children to adults. Neonatal TSH values are significantly higher in Salazie than in Lille (p < 0.005). Natural and mineral water, breast milk and salt contain little iodine. In conclusion iodine deficiency is present in this area of Reunion Island with a significant increment of neonatal TSH values.