Iron status was assessed by measurement of serum (S-) ferritin and hemoglobin (Hb) in 548 randomly selected healthy Danes (264 men, 284 women) with a median age of 25 years (range 16-31). S-ferritin values in men displayed a gradual increase with age, and at all ages, men had higher values than women. Iron deficiency (i.e., S-ferritin < 16 micrograms/l) was observed in 0.8%; none had iron deficiency anemia (i.e., S-ferritin < 16 micrograms/l and Hb < 129 g/l). Daily iron supplementation was used by 15.5%. The frequency of iron deficiency was 0% in supplement users vs 0.9% in nonusers. The frequency of preclinical hereditary hemochromatosis was 0.38%. There was a slight insignificant increase in S-ferritin values of women with age. Iron deficiency was observed in 14.7% of 16- to 19-year-olds, in 9.2% of 20- to 24-year-olds, and in 8.6% of 25- to 31-year-old women (p < 0.01), and iron deficiency anemia (i.e., S-ferritin < 16 micrograms/l and Hb < 121 g/l) in 14.7%, 3.4%, and 3.7%, respectively (p < 0.01). Daily iron supplementation was used by 21.5%. The frequency of iron deficiency in users was 4.9% vs. 10.8% in nonusers, and the frequency of iron deficiency anemia 1.6% in users vs. 5.8% in nonusers. The results indicate a satisfactory iron status in young men. There is a high frequency of iron deficiency in young women, suggesting that preventive measures should be considered in this risk group.