Multiple myeloma is a neoplastic disease of the immunoglobulin-producing plasma cells in the bone marrow. it is a rare disease in the cat, and diagnosis requires evidence of two of the following four criteria: 1) hypergammaglobulinemia with a monoclonal spike, 2) light chain proteinuria, 3) osteolytic bone lesions, 4) the bone marrow consist of greater than 5-20% plasma cells. This paper will act as a review of feline mutiple myeloma as well as present a case report on a 15 year old male castrated domestic medium haired cat diagnosed with mutlitple myeloma.