In order to assess the prevalence of iron deficiency in the Danish population, a randomised cross sectional investigation was carried out one year after repealing of the order from 1939 concerning supplementing of corn products with iron. A randomised group of 198 persons divided into ten groups of 20 persons with equal numbers of men and women in the age group 20-69 years was submitted to determinations of serum-iron, serum-transferrin and serum-ferritin. The prevalence of iron deficiency as determined by serum-ferritin values of below 15 micrograms/l was 18% and 12% respectively, for women under and over 45 years while iron deficiency determined by transferrin saturation under 16% was 18% for both groups. 6% of the women under 45 years had severe iron deficiency as determined by low transferrin saturation and low ferritin. The prevalence among men was 1% and 3% as assessed by serum-ferritin levels and transferritin saturation. These results were compared with corresponding population investigations from Sweden where iron enrichment is the highest in the world and the sale of iron tablets is the greatest in the world. No significant differences in the frequency of latent iron deficiency could be demonstrated but the number of persons with severe iron depletion appears to be less in Sweden. Differences in the methodological procedures, however, cannot be excluded.