The syndrome of CD8 hyperlymphocytosis with neutropenia is a heterogeneous disorder ranging from reactive benign state to neoplastic pathology. The prognosis for LGL (Large Granular Lymphocyte) leukemia depends likely on its phenotype:-NK phenotype, extremely poor prognosis and rapidly fatal-T phenotype (CD8+), chronic disease with slow progression. Here, we report four cases of CD8+ hyperlymphocytosis with neutropenia, which are CD2+/-, CD3+, CD4-, CD8+, CD16-, CD56+/-, CD57+ phenotype. These lymphocytic proliferations were associated with clonal rearrangement of T-cell receptor b gene. In two cases, characteristic blood hyperlymphocytosis appeared only after splenectomy, but retrospective bone marrow analysis showed that the CD8+, CD57+ lymphocyte proliferation previously existed. These lymphocytes had a low natural killer activity against K562 cell line. HTLV1 proviral sequence was not integrated in leukemic cell DNA. This monoclonal pathology has a chronic clinical course, with a thirteen year evolution in one case. Splenectomy did not correct neutropenia but allowed the control of hemolytic anemia and auto-immune thrombocytopenia in one case.