Gastrointestinal function, chiefly acid secretion by the stomach, was studied in 30 children with iron deficiency anemia and in 13 healthy children of comparable age. Sixteen of the anemic patients had an associated hookworm infection and in 14 the anemia was due to dietary iron deficiency. Gastric acidity was reduced in all of the anemic patients regardless of etiology and of whether observations were made under basal conditions or following stimulation with histamine. A direct effect of hookworm infestation could not be demonstrated either in terms of acid secretion or by biopsy of the small bowel. In these children anemia seemed vastly more important than damage wrought by hookworms in reducing acid secretion by the stomach. Additional observations on fecal fat and urinary xylose excretion did not yield definitive conclusions.