OBJECTIVE To evaluate the long-term efficacy and possible side effects of low doses of iodized oil on iodine nutrition and thyroid function in endemic goiter in Romania. METHODS Random selection of 214 schoolchildren aged 6-14 years. Serial measurements of urinary iodine, thyroid volume with ultrasound, serum concentrations of thyrotropin, free thyroxine, thyroglobulin and thyroid autoantibodies before and up to 2 years after the oral administration of 200 mg iodine in iodized oil. RESULTS Urinary iodine concentrations indicated a moderate iodine deficiency before therapy, sharply increased soon after therapy and slowly decreased thereafter but remained within the normal range up to more than 1 year after therapy. The prevalence of goiter was 29% before the administration of iodized oil and 9% 1 year later. Thyroid function tests and autoantibodies were normal before and up to 2 years after therapy. CONCLUSIONS A single dose of 200 mg iodine from oral Lipiodol appears adequate and safe for correcting moderate iodine deficiency in children.