Clinical and histopathologic findings were reviewed in 84 cases of malignant lymphoma of the small (well differentiated) lymphocytic type. The slides were studied without clinical information, and the following morphologic features were evaluated: pattern of growth, number of large lymphocytes, mitotic rate, degree of capsular involvement, presence of plasma cells and/or plasmacytoid lymphocytes, and presence of residual germinal centers. Subsequently, clinical information was obtained. The minimum follow-up period on living patients was 5 years. The patients were divided into 3 clinical categories: 1) monoclonal gammopathy (MG)-11 cases, 2) chronic lymphocytic leukemia (CLL) without MG-56 cases, and 3) those without MG or CLL at the time of lymph node biopsy-17 cases. The criterion for CLL was an initial absolute lymphocyte count less than 4000/mm3. Four of the patients with MG also had CLL, and 6 of those in the third group later developed CLL, from 1 to 61 months after lymph node biopsy. Generalized lymphadenopathy was the usual presentation in all 3 groups, and bone marrow examination was positive in all but 1 of the 49 cases, representing all 3 groups, in which it was performed. Median survival for the 84 patients was 51 months. The only clinical parameters which showed a significant association with poorer survival were age above 60 and anemia (Hb. conc. less than 11.0). There was no significant relationship between morphologic characteristics and clinical categories other than the association of plasmacytoid cells with MG in 6 cases. A mitotic rate of 30 or more mitoses per 20 high power fields (HPF), found in 5 cases with at least 1 in each clinical category, showed a highly significant association with decreased survival (p = .01). Variations in mitotic rate between 0 and 29 mitoses per 20 HPF and other morphologic parameters did not show a significant relationship with prognosis. It was concluded that malignant lymphoma of the small lymphocytic type is a definite clinicopathologic entity which may or may not exhibit MG or CLL, and it is proposed that the term "intermediate lymphocytic lymphoma" be applied only to those cases showing histopathologic characteristics of small lymphocytic lymphoma and a mitotic rate of 30 or more mitoses per 20 HPF.