Replacement therapy in adults, and children and adolescents (0-18 years) in: primary immunodeficiency (PID) syndromes with impaired antibody production; hypogammaglobulinaemia and recurrent bacterial infections in patients with chronic lymphocytic leukaemia, in whom prophylactic antibiotics have failed; hypogammaglobulinaemia and recurrent bacterial infections in plateau-phase-multiple-myeloma patients who have failed to respond to pneumococcal immunisation; hypogammaglobulinaemia in patients after allogeneic haematopoietic-stem-cell transplantation (HSCT); congenital AIDS with recurrent bacterial infections. Immunomodulation in adults, and children and adolescents (0-18 years) in: primary immune thrombocytopenia (ITP), in patients at high risk of bleeding or prior to surgery to correct the platelet count; Guillain-Barré syndrome; Kawasaki disease; chronic inflammatory demyelinating polyneuropathy (CIDP). Only limited experience is available of use of intravenous immunoglobulins in children with CIDP.