Although non-Hodgkin's lymphoma presenting with prominent splenomegaly is a well-recognized clinical syndrome, previous reports of such cases create confusion today because of the use of outdated pathologic classifications, awkward or inappropriate terms, and imprecise diagnostic criteria. The authors have studied 31 such cases and have classified them according to the modified Rappaport and Lukes-Collins classifications as well as the recently introduced International Working Formulation. Most of our cases (30/31) of malignant lymphoma presenting with prominent splenomegaly were of the small cell type, with morphologic and/or immunologic evidence of B-cell origin. The single largest subtype in our series (19/30) was intermediate lymphocytic lymphoma (IL), a recently described entity in which this mode of presentation has not been previously emphasized. Although such cases have been termed "primary splenic lymphoma," almost all are disseminated diseases that pursue a progressive course and require multiagent chemotherapy and/or radiotherapy.