This study reports the case of a patient who presented with evidence for a diagnosis of chronic myelogenous leukemia, as shown by blood and bone marrow analysis, and with generalized lymphadenopathy and splenomegaly. A lymph node biopsy revealed that the majority of the cells had plasmacytoid features but were consistently negative for surface or cytoplasmic immunoglobulin products, myelomonocytic surface markers, and peroxidase. Rather, lymph node plasmacytoid cells expressed T-cell markers (T 4/Leu 3+, T 10+), transferrin receptors (T 9+), and a proportion of them was also positive for sheep erythrocyte receptors (T 11/Leu 5+). This case is strikingly similar to a case reported by Lennert's group with respect to morphology, surface phenotypic features of the malignant plasmacytoid cells, and the association between a lymphoproliferative and a myeloproliferative disorder. This association suggests that plasmacytoid T-cells might exert a regulatory role on proliferation of myeloid cells.