Replacement therapy in adults, children and adolescents (0-18 years) in: Primary immunodeficiency syndromes with impaired antibody production. Secondary immunodeficiencies (SID) in patients who suffer from severe or recurrent infections, ineffective antimicrobial treatment and either proven specific antibody failure (PSAF)* or serum IgG level of < 4 g/L. *PSAF = failure to mount at least a 2-fold rise in IgG antibody titre to pneumococcal polysaccharide and polypeptide antigen vaccines. Immunomodulatory therapy in adults, children and adolescents (0 to 18 years) in: Chronic inflammatory demyelinating polyneuropathy (CIDP) as maintenance therapy after stabilization with IVIg.