Cryoglobulinemia means “cold antibody in the blood” and is the presence of abnormal antibodies that are soluble in the blood at body temperature but which precipitate out of the blood at lower temperatures in the laboratory. These antibodies are often present in patients with a wide variety of pre-existing diseases such as hepatitis C virus infection, autoimmune diseases such as rheumatoid arthritis or Sjögren’s Syndrome or cancers such as lymphoma or multiple myeloma. In the very rare cases where an underlying disease is not identified the presence of cryoglobulin antibodies in the blood is called “essential cryoglobulinaemia”. Often the antibodies do not cause any problems and then no treatment may be needed. In some patients they cause a vasculitis of the small and medium blood vessels called Cryoglobulinaemic Vasculitis. This condition may need treatment.