Non-Hodgkin lymphoma developing in patients with HIV infection fulfills diagnostic criteria for AIDS. Clinical manifestations of AIDS-NHL are similar to those of malignant lymphoma arising in other acquired and congenital immunodeficiency states. AIDS related NHLs therefore consist primarily of tumours with B cell phenotype, intermediate or high grade histological subtype and rapid clinical progression with a high frequency of unusual extranodal involvement. Treatment of AIDS-NHL has been much less rewarding than treatment of lymphoma in non-HIV infected individuals. Complete response rates are lower than the corresponding rates seen in the non-HIV infected population, and responses that do occur tend to be of short duration. Improvements in treatment for AIDS-NHL will require the use of new therapies, designed to cause less myelosuppression, in conjunction with aggressive efforts to prevent opportunistic infections.