A case of chronic neutrophilic leukaemia associated with multiple myeloma is reported. The patient had a 6 months history of bruising and weight loss, and showed mature neutrophilic leukocytosis, hepatosplenomegaly, high neutrophil alkaline phosphatase score, hyperuricaemia, neutrophils with pseudotoxic granulation and scarce Döhle bodies; moreover, a monoclonal IgG lambda was detected amounting 57.3 g/L. The bone marrow was grossly hypercellular with marked myeloid hyperplasia and aggregates of immature plasma cells. After treatment during 1 year with melphalan and prednisone she is well, although persisting with neutrophilic leukocytosis, slight splenomegaly, and the monoclonal IgG decreased to 25.8 g/L.