For many years, non-steroidal anti-inflammatory agents, steroids and immunosuppressive drugs have been the mainstay of treatment for rheumatological disorders. Over the last few years, the emergence of biologic treatments has dramatically changed the management of numerous rheumatological diseases. However, immunoglobulin treatment has been used for decades and its use has still not been superseded in certain rheumatological diseases. In fact, despite the introduction of newer immunomodulatory drugs, there has been an ever-increasing number of clinical indications for which intravenous immunoglobulin (IVIG) has been tried. Immunoglobulins are plasma proteins secreted by plasma cells, forming a major component of the adaptive immune system. IVIG is a blood product prepared from plasma, each batch prepared from a pool of 10,000-20,000 donations. Multiple purification steps during the manufacturing process aim to eliminate all known transmissible pathogens, but cannot completely exclude the risk from unknown pathogens. It should be noted that there has been the transmission of hepatitis C in one batch of immunoglobulin, reported in 1994, resulting in more than 200 patients in the USA and Europe being affected. Nevertheless, IVIG remains relatively safe compared with other immunosuppressive drugs. Headaches and fatigue are common side effects but fortunately the more severe problems such as aseptic meningitis, venous thromboembolism and acute renal failure remain rare. High-dose immunoglobulin when administered i.v. has immunomodulatory properties. The precise mechanism of action of IVIG is complex and not yet fully understood.