To evaluate the incidence of either evident anemia or a subclinical status of iron deficiency in celiac disease (CD), we studied 80 celiac children aged 6 months to 18 years. They were subdivided into various groups according to morphology of gut mucosa and diet. Only eight of 47 celiac children had an evident anemia at the time of the first peroral bowel biopsy. In addition, 51% of the patients with atrophic mucosa and 56% of the children on a gluten-containing diet had serum iron levels less than 50 micrograms/dl; 35% of patients of both groups had serum ferritin levels less than 12 micrograms/L. On the contrary, only a small number of children with normal mucosa on a gluten-free diet showed a laboratory, subclinical picture of iron deficiency. The results of our study can therefore be summarized in three major items: (a) Low levels of both serum iron and ferritin can frequently be found during active CD. (b) Regular determination of serum iron levels appears to be useful in controlling the state of iron stores in such patients, as well as in deciding whether and when to recommend temporary iron supplementation. (c) Serum ferritin tests did not offer more information than the easier and cheaper serum iron determinations.