The prognostic significance of phenotype in malignant lymphomas (ML) is a matter of controversy. Here we analyze the clinical presentation, response to treatment, and survival of the 361 phenotyped patients with ML who were treated by the LNH-84 regimen. Histologic subtypes were diffuse-small cell in 10 patients, diffuse mixed in 69, diffuse large-cell in 177, immunoblastic in 94, and anaplastic large-cell in 11. One hundred and eight patients (30%) had a peripheral T-cell ML and 253 (70%) a B-cell ML. Most of B-cell MLs were of diffuse large-cell type, and the T-cell MLs were distributed among diffuse mixed and immunoblastic subtypes. T-cell MLs had an aggressive presentation with more patients having advanced stage (21% versus 41% stage II, 53% versus 45% stage IV, p = .0002), and B symptoms (58% versus 42%, p less than .01). The only significant difference in clinical manifestations were the higher frequency of gastrointestinal involvement in B-cell MLs (20% versus 2%, p less than .0001) and the more frequent spleen (39% versus 21%, p = .0005) and skin (19% versus 3%, p less than .0001) involvement in T-cell MLs. There was no difference in response to the LNH-84 regiment between the two subgroups, but T-cell ML patients relapsed at a higher rate (43% versus 29%, p less than .001). T-cell ML patients have a significantly shorter freedom-from-relapse (FFR) survival (median: 34 months versus not reached, logrank test: p = .002) and a non-significant shorter overall survival (median: 42 versus 50 months).(ABSTRACT TRUNCATED AT 250 WORDS)