A case of immunoblastic lymphadenopathy like T cell lymphoma (IBL like T cell lymphoma) associated with biclonal gammopathy is reported. The patient is a 79 year-old male who was admitted to our hospital for generalized lymphadenopathy in January 1987. The lymph node biopsy revealed complete architectural effacement with replacement by a diffuse cellular infiltrate of immunoblasts and pale cells which have a T cell phenotype. A diagnosis of IBL like T cell lymphoma was made. Of interest, high serum level of IgG (6,630 mg/dl) was noted, and immunoelectrophoresis revealed biclonal gammopathy (IgG kappa, IgG lambda), but no remarkable abnormalities were found in the bone marrow aspiration and bone survey. We treated the patient with two courses of CHOP therapy, which resulted in marked improvement of generalized lymphadenopathy and disappearance of biclonal gammopathy. However, relapse was noted a month later without reappearance of biclonal gammopathy. The rebiopsy of lymph node revealed a new appearance of Lennert's lesions and decrease of immunoblasts in number. The patient received two courses of M-BACOD therapy, which achieved complete remission, and the patient remained in remission for more than 17 months.