Studies of dietary habits show a high iodine intake in children in Denmark. Iodine excretion in children has not previously been assessed. Iodine excretion in adults is below the recommended threshold, and it is therefore being discussed to increase the fortification level. The main objective of this study was to assess iodine excretion in children living in Copenhagen to establish whether a moderate increase in iodine fortification would lead to excess iodine intake in this group.Children in first and fifth grade were recruited through schools in Copenhagen. In total, 244 children de-ivered a urine sample. Urine samples were analysed for iodine and creatinine, and the results were expressed as urinary iodine concentration (UIC) and as estimated 24-h iodine excretion. Iodine excretion in children was also compared with that of adults living in the same area, investigated in a prior study.The median UIC was within the recommended level; 145 (range: 116-201) µg/l for boys and 128 (range: 87-184) µg/l for girls, and was lower in fifth grade students than in first grade students. Estimated 24-h iodine excretion was higher in boys than in girls, but did not differ according to grade. The UIC was higher in children than in adults from the same area.The iodine excretion among schoolchildren in Copenhagen, an area with a relatively high iodine content in tap water, was within the recommended range as assessed by the UIC. An increased iodine fortification will not have negative consequences for this group.The Ministry of Food, Agriculture and Fisheries.not relevant.