Monoclonal Gammopathy of Undetermined Significance (MGUS) is a build up of monoclonal antibodies produced by abnormal but non-cancerous plasma cells. In general, MGUS does not cause significant health problems and is almost always discovered by chance when laboratory tests are performed for other purposes. In this article, Drs Siva Ramakrishnan and Venkitasamy Balakrishnan discuss the diagnosis and management of MGUS in the elderly.