The neoplastic proliferation of single clones of plasma cells causes synthesis of very large amount of monoclonal immunoglobulins consisting of only one type of heavy either the gamma, alpha, mu, delta or epsilon chain or only kappa or lambda light chains. Each monoclonal immunoglobulin differs idiotypically from each other. These monoctonal immunoglobulins are also called paraproteins and are frsquentiy associated with a broad heterogeneous group of plasma cell dyscrasias. Occasionally their presence is observed in a few benign conditions and in old age. In the present review a detailed account of different types of monoclonal gammapathies are describsd.