Nodular histiocytic lymphoma (NH) is uncommon, and its natural history is not well defined. Of 473 patients with non-Hodgkin's lymphoma, we found 16 (3.4%) with NH. Most patients (13/16) presented with pathologic stage (PS) III or IV disease, including 7 with liver involvement. One patient (PS III) was initially treated with cyclophosphamide alone, and 4 patients received only radiotherapy, and none were long-term survivors. Eleven patients received combination chemotherapy, and 8 achieved complete remission. Only one of these patients relapsed and died at 19 mo; the other 7 continue in complete remission without maintenance therapy with a minimum followup of 4.5 yr. The survival of the entire group of patients with NH is intermediate between that of the other nodular lymphomas and diffuse histiocytic lymphoma. Nine of 16 patients had either a repeat lymph node biopsy during the course of their disease or lymph node examination at autopsy. Lymph node histology in the majority converted to a diffuse, less differentiated subtype of lymphoma. NH has a natural history similar to that of diffuse histiocytic lymphoma and should be approached with the same therapeutic strategy.