We analyzed 23 cases of T-cell-rich B-cell lymphomas (BCL) to determine if the clinical features are characteristic of a discrete entity. Cases encoded as T-cell-rich BCL in the hematopathology archives of the University of Texas M.D. Anderson Cancer Center between 1988 and 1991 formed the basis of this study. At least 50% of the total population of cells were required to be of T-cell phenotype. Actually, all but one patient had more than 70% T cells in the total population. Sixty-five percent of all cases were referred with other diagnosis such as Hodgkin's mixed cellularity, peripheral T-cell lymphoma (PTCL), or diffuse mixed lymphoma, and had received therapy accordingly. With the exception of splenomegaly, which occurred in 35% of cases, the other clinical characteristics and the response to therapy did not indicate that this entity represents a distinct type of lymphoma. Ann Arbor stage I-II presentations were seen in 10 of 23 (43%) T-cell-rich BCLs. Serum lactate dehydrogenase (LDH) was elevated in eight of 19 patients. Age, sex, and beta 2-microglobulin were not significantly different from classical B-cell large cell lymphoma. The clinical presentation and clinical outcome of T-cell-rich BCL did not differ from that of common B-cell large cell lymphoma, except for the higher proportion of splenomegaly seen in patients with T-cell-rich BCL. The presence of the T-cell-rich infiltrate varied: it frequently was not seen at relapse or at other sites of disease at presentation. It was thus considered an unstable parameter. The major importance of identifying this entity is to distinguish it pathologically from other disorders such as Hodgkin's disease and PTCL, which would be treated in a different manner.