Taiwan was an iodine deficiency area and endemic goiter was common in 1940's. Mandatory salt iodization started in 1967, and a 1971 survey indicated that goiter rates in children decreased from 21.6% to 4.3%. To understand iodine status before the change of national salt iodization program in 2003, from mandatory to voluntary salt iodization, we retrospectively measured urinary iodine concentrations of samples collected from children in the Nutrition and Health Survey in Taiwan 2001-2002. The median UI level for children aged 6-12 years was 123 μg/L (no differences between males and females). Females aged 10-12 years had the lowest urinary iodine levels. The percentages of this population with urinary iodine levels below 100, 50, and 20 μg/L were 35.2%±1.0%, 4.4%±0.4%, and 0.2%±0.1%, respectively. Older children were more likely to have low urinary iodine levels. People living in different areas of Taiwan had a median urinary iodine levels ranged from 113 μg/L to 164 μg/L (males: 113-153 μg/L; females: 105-174 μg/L), with the highest level in Penghu islands, and the lowest level in the eastern and southern (Southern area 2) areas. According to international criteria, iodine status in 2001-2002 was adequate, comparable to the surveyed goiter rates (4.3%, classified as iodine sufficiency) in 1971, inferring that iodine nutrition remained adequate and stable during this period. The present study is of great importance in documenting the iodine status of Taiwan before the change from mandatory to voluntary salt iodization to serve as a baseline data for future trend analysis in iodine nutrition.