Iron status, iron absorption, and intestinal blood loss were studied in 199 children undergoing diagnostic evaluation for suspected malabsorption. Evaluation of iron status included hematological indices, serum ferritin, and transferrin saturation. Iron absorption was assessed by the increment of serum iron after an oral iron load. Iron deficiency was common among patients affected by malabsorptive states, such as celiac disease (84%), cow's milk intolerance (76%), Crohn's disease (72%), and giardiasis (64%), whereas it was less common among patients with postinfectious enteritis (41%) and chronic nonspecific diarrhea (11%). Intestinal blood loss was seen only in patients with Crohn's disease and cow's milk intolerance, irrespective of iron nutritional status. On the other hand, iron malabsorption was very common, affecting 85-95% of the iron-deficient patients in all diagnostic groups, except in chronic nonspecific diarrhea. Iron malabsorption was less common among patients with adequate iron nutritional status than in those with iron deficiency. Iron malabsorption appears to play a major role in the pathogenesis of iron deficiency in patients with malabsorption. The iron absorption test shows greater sensitivity as a screening test for upper intestinal malabsorption than the D-xylose absorption test.