Intravenous immunoglobulin (Ig IV) has been used for many years in the treatment of primary antibody deficiencies. We performed a retrospective study of the clinical features and outcome of agammaglobulinemia children who received prolonged IgIV infusions. Patients and methods: Ten children,9 male et 1 female, with agammaglobulinemia diagnosis were studied for the clinical manifestations before and during the IgIV replacement therapy. Serum Ig levels were quantified by nephelometry. Circulating B and T cells were counted by immunofluorescence labeling by monoclonal antibodies. T cell fonctions were assessed by using mitogen and antigen-induced T-cell proliferation assays in vitro. Patients clinical status was evaluated respectively, before initiation and at every moment (when patients had an infection) of the replacement therapy. Results: IgIV therapy was performed for 866 cumulated months, median 108 months. The median IgIV doses administered to the 10 patients was 500 mg/kg/month.Residual serum IgG mean level was 3,9 g/L. All patients had 99 bacterial infections/ year before Ig IV, mainly respiratory tract infections (48,5%), and 4 patients had bronchiectas is before Ig replacement therapy. The number of infection /year fall to 25 during IgIV replacement, and the infection/patient/year rate decreases significantly. One patient developed an Echovirus 27 meningoencephalitis during this treatment. Conclusion: IgIV therapy with residual IgG mean level of 3,9 g/l reduced significantly the rate of bacterial infections. The use of specific antibiotherapy and respiratory kinesitherapy led to a lower rate of respiratory tract infections, and the stabilisation of the bronchiectasis.However this intravenous replacement therapy does not protect against viral meningoencephalitis. We performed a retrospective study of the clinical features and outcome of agammaglobulinemia children who have prolonged IgIV infusions. Patients and methods: Ten children, 9 male et 1 female, with agammaglobulinemia diagnosis were studied for the clinical manifestations before and during the IgIV replacement therapy. Serum Ig levels were quantified by nephelometry. Circulating B and T cells were counted by immunofluorescence labeling by monoclonal antibodies. T cell fonctions were assessed by using mitogen and antigen-induced T-cell proliferation assays in vitro. Patients clinical status was evaluated respectively, before initiation and at every moment (when patients had an infection) of the replacement therapy. Results: IgIV therapy was performed for 866 cumulated months, median 108 months. The median IgIV doses to the 10 patients was 500 mg / kg / month. Res All patients had 99 bacterial infections / year before Ig IV, mainly respiratory tract infections (48,5%), and 4 patients had bronchiectas before before Ig replacement therapy. The number of infection / year fall to 25 during IgIV replacement, and the infection / patient / year rate decreased significantly. One patient developed an Echovirus 27 meningoencephalitis during this treatment. Conclusion: IgIV therapy with residual IgG mean level of 3,9 g / l reduced significantly the rate of bacterial infections. The use of specific antibiotherapy and respiratory kinesitherapy led to a lower rate of respiratory tract infections, and the stabilization of the bronchiectasis. Host this intravenous replacement therapy does not protect against viral meningoencephalitis.