The premise that chronic antigenic stimulation may be involved in lymphoproliferative disorders was considered in a patient with immunoblastic lymphadenopathy who had received liver extract by injection and by mouth for many years. The salient features were lymphadenopathy and hepatosplenomegaly, a predominance of lymphocytes and plasmacytoid cells with mitotic figures in lymph-node imprints, a cryoglobulin containing IgG, IgA, IgM and bound complement components, depressed serum complement levels, and Coombs-test-positive erythrocytes. Immunoglobulin concentrations per 100 ml of serum were IgG, 5900 mg, IgA, 1480 mg, and IgM, 5640 mg, with normal ranges of 710 to 1540, 60 to 490, and 37 to 204 mg, respectively. Serum precipitins to an antigen (or antigens) in the liver extract resided in the IgA and IgM classes. Complete remission followed one course of cyclophosphamide, vincristine, and prednisone. We propose that the syndrome was caused by chronic antigenic stimulation with liver extract.