A case report of simultaneous presentation of chronic neutrophilic leukemia and multiple myeloma (IgG kappa) in a 71-year-old male is described. The patient showed mature neutrophilic leukocytosis, hepatosplenomegaly, high neutrophil alkaline phosphatase score, hyperuricemia, neutrophils with toxic granulation and Dohle bodies, absence of Philadelphia chromosome and of the bcr-abl fusion gene. Moreover, a monoclonal IgG kappa paraproteinemia (36.93 g l(-1)) was detected. Bence-Jones proteinuria was 3.84 g l(-1). The bone marrow was grossly hypercellular with marked myeloid hyperplasia and aggregates of plasma cells. The patient died of severe bronchopneumonia after the transformation of chronic neutrophilic leukemia to acute myelomonocytic leukemia, 1.5 years following diagnosis.