BACKGROUND: Mild deficiencies and excesses of iodine have deleterious effects in both females and males. The iodine status of the population after implementation of the universal salt iodization program in Sri Lanka is not known. OBJECTIVE: This cross-sectional study was carried out to assess the iodine status of pregnant women and female adolescents, with urinary iodine concentration used as the measure of outcome. METHODS: The participants were 100 women in the first trimester of pregnancy and 99 female adolescents in Kuliyapitiya, Kurunegala District, North-Western Province, Sri Lanka. The urinary iodine concentration was measured in a casual urine sample from each subject. The iodate contents of salt samples collected from households of the adolescents participating in the study were also measured. RESULTS: The median urinary iodine concentration of 185.0 microg/L and the prevalence of values under 50 microg/L of only 1% among the pregnant women indicate adequate iodine intake and optimal iodine nutrition. The median urinary iodine concentration (213.1 microg/L) among female adolescents indicates a more than adequate iodine intake and a risk of iodine-induced hyperthyroidism. Approximately 8% and 4% of the adolescents and pregnant women, respectively, had urinary iodine concentrations in the range of mild iodine deficiency (51 to 100 microg/L). More than half of the adolescents (56%) and 39% of the pregnant women had urinary iodine concentrations higher than optimal. The median iodine content in salt samples was 12.7 ppm. Only 20.2% of the samples were adequately iodized, and 10.1% of the samples had very high iodine levels. CONCLUSIONS: Female adolescents and pregnant women had no iodine deficiency, but a considerable proportion of them, especially female adolescents, were at risk for iodine-induced hyperthyroidism. There is thus a need for proper monitoring of the salt iodization program to achieve acceptable iodine status.