A series of 377 low-grade non-Hodgkin's lymphomas, observed in the same Institute, was analysed. Pathological types following the Kiel classification were crossed with the usual parameters of patients (sex, age) and disease (tumoural extension, main anatomical involvement, biological data, course of the disease). Small differences appeared for the survivals for the overall series. By contrast many significant differences were observed for sex, age, dissemination of the disease, special tissue involvement, monoclonal gammopathy, complete remission rate and further involvement in case of relapse. These parameters allow one to distinguish different clinicopathological entities after the morphological cellular features. Such correspondences appear meaningful and might be offered by any other classification which should not be based only on the prognosis.