Immunoblastic lymphadenopathy (IBL)-like T-cell lymphoma is a distinct peripheral T-cell lymphoma, which closely resembles angioimmunoblastic lymphadenopathy with dysproteinemia (AILD) and/or IBL, but is characterized by focal or sheet-like proliferation of immunoblasts and pale cells of T-cell nature. In this report, 36 patients with IBL-like T-cell lymphoma were analyzed. The disease is clinically characterized by generalized lymph node swelling, hepatosplenomegaly, fever, skin rash, polyclonal hypergammaglobulinemia, marked male predominance, predilection for the elderly, and poor prognosis. There was no association with human T-cell leukemia virus type I or human immunodeficiency virus. IBL-like T-cell lymphoma may be divided into two categories (CD4+ type and CD8+ type) by surface marker analysis. It can also be divided into three categories on the basis of the histologic findings of distribution of morphologically recognizable tumor cells: nine cases of "inconspicuous type," six cases of "patchy type," and 21 cases of "diffuse type." Two cases of "inconspicuous type" converted later to "diffuse type." DNA hybridization analyses in the ten recent cases revealed that three of four "inconspicuous types" and five of six "diffuse types" showed clonal rearrangement of T-cell receptor-beta chain gene without rearrangement of immunoglobulin heavy chain gene, providing strong evidence for clonal proliferation of T cells.