Goiter examination was performed on 7,785 children aged 9 to 16 years in four areas of the United States--Michigan, Kentucky, Texas, and Georgia. Urinary iodine and creatinine, thyroxine, protein-bound iodine, and plasma inorganic iodide determinations were made on 377 matched pairs of goitrous and nongoitrous control children. The overall prevalence of goiter was 6.8%. Most children with goiter had palpably but not visibly enlarged thyroids and showed no evidence of clinical or biochemical thyroid abnormalitymmean urinary iodine excretion was 452 mug/gm of creatinine, many times the 50 mug/gm of creatinine level used to define deficiency. Children with goiter and areas with high goiter prevalence tended to have higher rather than lower iodine excretion. These findings are consistent with other data indicating high iodine intakes in the United States and suggest that goiter in American children cannot be assumed to be related to iodine deficiencymthe possible role of high iodine intake in the causation of goiter is discussed.