Monoclonal gammapathy is a condition that may be related to the malignant lymphoproliferative disease, but more often to a benign lymphoproliferation. Formerly termed benign monoclonal gammapathy it is now called monoclonal gammapathy of unknown significance (MGUS), because years later malignant lymphoproliferative disease may develop. Even benign gammapathy may cause frequent symptoms in a patient. The text describes clinical manifestations of monoclonal protein including various differential diagnostic possibilities.

        Key words: Monoclonal gammapathy - Multiple myeloma.