Infection with HIV is associated with an increased risk of systemic and primary central nervous system non-Hodgkin's lymphoma. Patients with systemic non-Hodgkin's lymphoma usually present with high- or intermediate-grade histology and extranodal dissemination. Although the prognosis for such patients is poor, some patients clearly benefit from combination chemotherapy, and several new treatment approaches appear promising. Primary central nervous system lymphoma usually occurs in patients with more profound immunosuppression and is associated with a dismal prognosis. Selected patients with good performance status may benefit from therapy, particularly if opportunistic infections have been few and nondebilitating. Finally, Hodgkin's disease has been reported in patients with HIV infection, particularly in patients with a history of intravenous drug use, and it is more likely to present with advanced-stage disease and unfavorable histology.