The number of cases HIV-associated non-Hodgkin's lymphoma continues to increase as the AIDS epidemic grows. Approximately 3% of AIDS-defining illnesses are non-Hodgkin's lymphoma. The number of non-Hodgkin's lymphoma cases may actually be higher because many cases go unreported. There is also evidence that increasing numbers of patients who are surviving longer on antiretroviral therapy are developing non-Hodgkin's lymphoma. A majority of HIV-related lymphomas are large cell, either high-grade immunoblastic or aggressive intermediate grade, diffuse cleaved, or small noncleaved (Burkitt's-like). HIV-related non-Hodgkin's lymphomas behave aggressively. They are predominantly extranodal and often show unusual patterns of organ involvement. They are typically stage III or IV at the time of diagnosis. Current treatment strategies involve the use of combination chemotherapy regimens with or without antiretroviral therapy. Current studies are evaluating the efficacy of low-dose chemotherapy regimens versus standard-dose regimens with granulocyte-macrophage colony-stimulating factor support. New strategies for treating AIDS-associated non-Hodgkin's lymphoma will incorporate our current knowledge of AIDS-related lymphoma pathogenesis. Factors that reflect a patient's state of immunodeficiency seem to be the most important prognostic features determining clinical outcome after treatment. Patients with good prognostic features may benefit the most from aggressive treatment regimens. AIDS-related primary central nervous system lymphomas continue to comprise approximately 15% of AIDS-related non-Hodgkin's lymphoma cases. Treatment is limited. Although whole-brain radiation therapy can result in an improved neurologic status, the median survival remains 3 to 4 months.(ABSTRACT TRUNCATED AT 250 WORDS)