A long-term study of six children suffering idiopathic pulmonary hemosiderosis (IPH) was realized, in order to evaluate prognostic factors and the best therapy. The treatment was initiated with prednisone 1-2 mg/kg/day which was gradually decreased until total suppression. Clinical remission was always achieved but relapses were frequently observed. All but one of the patients suffered more episodes which were controlled by the initial treatment. In three cases the additional use of immunosuppressors drugs was needed, chlorambucil 0.2 mg/kg/day during a period of 3-6 months or cyclophosphamide 2.5 mg/kg/day for four months, thereby obtaining a better control of the disease and also a decreased number of crises. Two patients died during acute exacerbations. It is suggested that the main risk factors are the male sex and onset before three years of age. The outcome was also worse when the first crisis was more severe.