Prepared from the collective plasma of several thousand people, therapeutic intravenous immunoglobulin (IVIg) consists mostly of human polyspecific IgG. In addition to its use in primary and secondary immune deficiencies, IVIg is used in the treatment of several rheumatic conditions, including Kawasaki disease, dermatomyositis and antineutrophil cytoplasmic antibody (ANCA)-positive vasculitis. In these diseases, IVIg therapy generally involves the use of 2 g/kg administered over either 2 or 5 consecutive days. However, dosage regimens have not been thoroughly explored, and indications for IVIg in most rheumatic diseases, such as systemic lupus erythematosus, polymyositis and catastrophic antiphospholipid syndrome, derive from its off-label usage. Randomized clinical trials are warranted to support the evidence-based use of IVIg, and to identify the ideal administration protocols to maximize the benefits of what is a limited resource. Further research to improve the therapeutic application of IVIg relies essentially on the conception of next-generation immunoglobulin preparations and optimization of combined therapies with immunomodulatory drugs and biologic agents.