Helicobacter pylori is recognized as a major gastrointestinal pathogen in developing countries. This microorganism infects up to 60% of children less than five years in those countries and is strongly associated with chronic gastritis and peptic ulcer disease in children and adults. The progression of gastritis to atrophy often leads to decreased gastric acid output, which is a well-known risk factor for anemia. Gastric acid is essential for increasing the bioavailability and absorption of non-heme dietary iron, the most important source of iron in developing countries. Numerous reports suggest that iron malabsorption secondary to low gastric acid output is a problem in developing world countries. It has been further observed that iron deficiency anemia is resistant to iron therapy particularly in these countries. In a recently completed study we observed an association of anaemia with H. pylori infection. We hypothesize that the poor bioavailability of iron in these countries could be related to H. pylori -induced low gastric acid output and we propose to investigate the role of H. pylori infection as a cause of anemia and treatment failure of iron supplementation in Bangladesh. A prospective, randomized, double-blind, placebo-controlled field trial is proposed among four groups ( 65 each) of H. Pylori infected children of 2-5 years of age with iron deficiency anemia. The children will be assigned to one of the four therapies: antibiotics alone (for H. Pylori eradication), antibiotic plus iron therapy, iron therapy alone, or placebo. Hemoglobin concentration, serum ferritin concentration, and transferrin receptor will be measured before and at 1 and 3 month after the intervention. We also propose a complementary study in an additional 20 children with H. Pylori infection and iron deficiency anemia to assess iron absorption with application of double stable isotopes. The change in hematological parameters will also be compared among the groups before and after the therapy. The results of this study are expected to have implications in the prevention and treatment of iron deficiency anemia in developing countries.