The clinical course of two patients with prolymphocytic leukemia of the suppressor T-cell phenotype is presented. Diagnosis was established by specific monoclonal antibody tests, cytochemical, ultrastructural and cytogenetic studies. The bone marrow showed a diffuse infiltration with medium sized lymphocytes displaying a prominent nucleolus. Both patients presented with pronounced splenomegaly, diffuse lymphnode involvement, leukocytosis, thrombocytopenia and anemia. One of them was refractory to chemotherapy using CHOP, Asparaginase, IMVP16, and irradiation to the spleen. He benefited from prednimustin and repeated leukaphereses, without reaching complete remission (C.R.). The second patient achieved a C.R. of 4 months duration with CHOP-Bleomycin. Survival was 16 and 11 months respectively.