Linkage of AIDS and cancer registries has indicated an increase in T-cell lymphomas among individuals infected with the HIV. The characteristics of T-cell versus B-cell lymphoma in HIV-infected patients are not well described. Retrospectively, 11 cases of T-cell lymphoma were identified from the AIDS-Lymphoma Registry at the University of Southern California. These patients were compared with 418 consecutive HIV-seropositive patients with B-cell lymphoma diagnosed and treated within the same time period. T-cell lymphomas comprised 3% of all AIDS lymphomas. Pathologic types included peripheral T-cell lymphoma in 5; anaplastic large cell lymphoma in 3; and angioimmunoblastic, enteropathy type, and human T-cell lymphotropic virus-I-related adult T-cell lymphoma/leukemia in 1 case each. No differences in demographic characteristics, history of prior opportunistic infection, or immunologic characteristics were observed between T-cell and B-cell cases. Extranodal involvement of the skin (36% vs. 2%, P < 0.001) and bone marrow (45% vs. 15%, P = 0.019) was significantly more common in T-cell lymphomas. The median survival of patients with T-cell lymphomas was not significantly different from that of B-cell lymphoma patients (10.6 vs. 6.6 months, P = 0.13). T-cell lymphomas in HIV-infected patients represent a spectrum of pathologic types. T-cell lymphomas differ from B-cell cases in terms of a higher propensity for skin and bone marrow involvement. The median survival of patients with T-cell lymphoma is comparable to that of patients with B-cell AIDS-related lymphoma.