We report on a case of CD20-positive peripheral T cell lymphoma. The lymphoma cell was positive for CD20 and T cell lineage markers such as cytoplasmic CD3, CD4, and CD5 and had a monoclonal rearrangement of the T cell receptor (TCR) gamma chain gene. The clinical characteristics resembled angioimmunoblastic lymphadenopathy: spontaneous regression of lymphadenopathy and immunological abnormalities such as polyclonal hypergammaglobulinemia, positive results of direct and indirect antiglobulin tests, and a high antinuclear antibody titer. We reviewed seven cases of CD20-positive T cell malignancies including the present case. Three were immature T cell malignancies (acute lymphoblastic leukemia) and four were peripheral T cell malignancies (non-Hodgkin's lymphoma and chronic lymphocytic leukemia). Hepatomegaly and/or splenomegaly were common features. Further cases must be evaluated to understand the clinical significance of the CD20 expression on the surface of T cell malignancies.