Primary isolated bone marrow Non Hogikin`s lymphoma is very rare and poor prognosis. T-cell rich diffuse large B-cell lymphoma is rare entity as variant diffuse large B cell lymphoma representing 1%-3% of all diffuse large B cell lymphoma. Diagnosis is difficult, as it may appear similar to other lymphoid diseases. for accurate diagnosis, must performed careful immunohistochemical analysis of tumor cell and the inflammatory mic environment. It occurs in younger patients, predominantly affects men, and involve the liver, spleen, and bone marrow. T cell rich diffuse large B-cell lymphoma should be treated similary to other stage matched diffuse large B cell lymphoma. A 50-year old man was transfered to our hospital presenting with fever over 2 weeks despite of broad spectrum antibiotics. labolatory finding showed pancytopenia, elevated c-reactive protein and no growth bacteria in blood. The bone marrow examination done, and biopsy revealed involvement with T cell rich diffuse large B-cell lymphoma. A computed tomographic scan (CT) showed splenomegaly, but no lymphadenopathy. Positron emission tomography (PET) showed diffuse bone hot uptake without lymphadenopathy We confirmed diagnosis of primary bone marrow isolated T-cell rich diffuse large B-cell lymphoma. We treated with R-CHOP regimen for six cycle, and then autuologous peripheral blood stem cell transplantation. After 2 month, T- cell rich diffuse large B-cell lymphoma is recurred at Liver, bone. so we performed 2nd line chemotherapy as ESHAP regimen we described case of primary isolated bone marrow T- cell rich diffuse large B-cell lymphoma with FUO.