We identified 105 patients with lymphoid neoplasia associated with the acquired immunodeficiency syndrome (AIDS) at the New York University Medical Center from 1981 through 1986: 89 had non-Hodgkin lymphoma; 13, Hodgkin disease; and 3, chronic lymphocytic leukemia. Immunophenotypic and antigen receptor gene rearrangement analysis showed the B-cell origin of all non-Hodgkin lymphomas studied and the clonal suppressor-cytotoxic T-cell subset origin of the chronic lymphocytic leukemias. We classified 69% of the non-Hodgkin lymphomas as high grade (small, noncleaved and large cell, immunoblastic-plasmacytoid) and 31% as intermediate grade (diffuse large cell). Each histopathologic category was correlated with distinct clinical features, including a statistically significant difference in median survival. Patients with Hodgkin disease had an atypical, aggressive clinical course, whereas patients with T-cell chronic lymphocytic leukemia had an indolent clinical course. These studies show the clinical, morphologic, and immunophenotypic spectrum of AIDS-associated lymphoid neoplasia, that the natural history of Hodgkin disease is altered in patients with AIDS, and support the Centers For Disease Control's recent revision in diagnostic criteria for AIDS to include intermediate-grade diffuse, aggressive non-Hodgkin lymphomas occurring in patients seropositive for human immunodeficiency virus.