To extend the clinical-pathologic description of small cleaved cell lymphoma (SCCL), we reviewed the records of 106 patients with SCCL who were treated in accordance with a policy of watchful waiting and palliative therapy. Median age was 58 years. A pure diffuse pattern was seen in only 16 per cent of cases. Stage III or IV disease was present in 85 per cent of patients; marrow involvement was noted in 60 per cent of patients. 'B' symptoms were present in 25 per cent of patients. By univariate analysis, age greater than 60, diffuse pattern, stage IV disease, involvement of liver, lung, pleura, or g-i tract, 'B' symptoms, surface heavy chain IgM or IgM-D, and LDH greater than 200 IU/dl were found to be significantly associated with a poor prognosis. Marrow involvement, increased (5-25 per cent) transformed (non-cleaved) cells, and surface light chain had no prognostic significance. By multivariate analysis, only age greater than 60, stage IV disease, and LDH greater than 200 IU/dl were prognostically significant. For patients with all three unfavourable prognostic features, median survival was only 11 months. For patients with age less than or equal to 60, stage I, II, or III disease, and LDH less than or equal to 200 IU/dl, median survival was not reached at 180 months. Recognition of prognostic features in indolent lymphoma can help clarify whether the results of treatment protocols represent true advances or the mere selection of favourable patients.