Multiple myeloma is a plasma cell tumor that affects the bone marrow B lymphocytes. The abnormal plasma cells proliferate and produce monoclonal proteins which may accumulate in blood or urine (Bence-Jones proteins). Multiple myeloma will propagate and eventually replace normal plasmacytes leading to extensive bone destruction which may provoke fractures. Radiolucent "punched-out" lesions of the bone are typical findings. Anemia, renal insufficiency, hypercalcemia and amyloidosis are the most frequent clinical features of the disease. Oral manifestations of multiple myeloma are infrequent. The dentist may play a key role in the detection of this disease since oral lesions may lead to the discovery and diagnosis of the disease. The aim of this thesis is to describe three cases with oral manifestation and specifically review the literature on multiple myeloma.