The results suggest that iodized salt is an effective means of improving iodine status, and support the current endeavors to achieve universal salt iodization. Variations in the iodine levels in the salt suggest that particular care must be taken to ensure the quality of the production and storage of iodized salt. It appears that in small children salt intake may not be high enough to guarantee adequate iodine levels through the use of iodized salt. While the studies provided no information about unwanted side effects with the use of iodized salt, most studies did not specifically consider adverse effects. so inferences about side effects remain weak. In conclusion, health policymakers and other decision makers require high-quality studies to measure the effect of iodized salt in comparison with other forms of iodine supplementation. These should be large studies lasting at least two years. Investigators should not retstrict their outcomes to goiter rates and urinary iodine excretion, but should include the other outcome measures specified above, such as mental and physical development in children, mortality, and others. Investigators should pay special attention to adverse effects and their report in primary studies, and should assess children (including very young children who may have a relatively low salt consumption) separately from adults.