Severe iron deficiency anemia, pulmonary infiltrates, and cutaneous hemorrhage associated with thrombocytopenia developed in a 7-year-old girl. A typical clinical course and the presence of abundant hemosiderinladen macrophages in the gastric juice and alveoli suggested a diagnosis of idiopathic pulmonary hemosiderosis (PH). Investigation of the marked thrombocytopenia, not previously reported as a finding in IPH, resulted in the demonstration of antiplatelet antibody in the patient's serum and on her platelets. Response to corticosteroid administration and splenectomy was consistent with idiopathic thrombocytopenic purpura (ITP). The IPH and ITP may have occurred coincidentally in this patient, but certain pathophysiological similarities between these two disorders and ultimate development of a poorly defined fatal diffuse connective tissue disorder suggest that thrombocytopenia and intrapulmonary hemorrhage were related.