Severe iodine deficiency causes stunting and mental retardation in utero, but the relation between mild deficiency and child growth is not well known. The use of iodated salt in relation to anthropometric data was examined from recent survey data. After potential confounding factors had been controlled for, significant associations were seen in Bangladesh, India, Nepal, and Sri Lanka. The use of iodated salt was related to increased weight-for-age and mid-upper-arm circumference, most strongly in the second year of life, mainly affecting soft tissue (thinness).The relation with weight-for-age was greater among children of mothers with lower body mass index. The use of iodated salt was related to birthweight in Sri Lanka andin the Philippines, where iodated oil capsules given during pregnancy had a negative effect when used with high levels of iodine in salt. The associations generally were concentrated in large geographic areas, possibly because of interactions with other environmental factors (eg,selenium and arsenic). The apparent growth response to iodine may reflect functional effects of mild deficiency, which is widespread, possibly including effects on brain development.