We grouped 162 patients wtih advanced, diffuse histiocytic lymphoma (DHL) into various morphological subtypes to ascertain whether there were any significant differences in survival among them. These patients were staged and treated from 1972 to 1977 according to the protocols of the Southwest Oncology Group. Of the 159 patients on whom a consensus on the diagnosis was reached, 115 were classified morphologically as having large non-cleaved, 26 as B-immunoblastic, 9 as large cleaved, and 6 as T-immunoblastic. The 3 remaining patients did not fit any of these subtypes, but each had a single prominent nucleolus in most tumor cells (“prominent nucleolus” type). Morphological subdivision of DHL did not identify any subgroup of patients with a significantly longer survival, but clinical parameters such as stage, symptoms, and type of treatment significantly influenced survival times.