Most treatment procedures in AIDS-related lymphomas disclose a relatively poor outcome for patients with low response rates, high number of relapses and AIDS events. The addition of rituximab to the standard regimen - CHOP could improve the outcome of these patients. The aim of the trial is to evaluate the safety and efficacy of rituximab when added to the CHOP regimen in patients with newly diagnosed AIDS-related non-Hodgkin lymphoma.

HIV infection is associated with a high incidence of AIDS-related lymphomas (ARL). Since the use of highly active antiretroviral therapy (HAART), the incidence of AIDS-defining illnesses has decreased, leading to a significant improvement in survival of HIV-infected patients. The incidence of ARL has decreased in a lower degree and lymphoma remains the major cause of death of HIV patients. Most treatment procedures disclose a relatively poor outcome of patients with low response rates, high number of relapses and AIDS events. Since the majority of HIV-associated NHL are CD20-positive the addition of rituximab to the standard regimen - CHOP could improve the outcome of these patients

Inclusion Criteria:

• HIV positive with a high grade Ann Arbor stage I to IV untreated non-Hodgkin's lymphoma of B-cell origin confirmed by biopsy. The following histologies are eligible: *Burkitt's lymphoma, *diffuse large B-cell with standard histological diagnosis, *Burkitt-like and high grade large cell immunoblastic lymphoma with immunophenotyping CD20 positive
• Good and intermediate prognostic group (no more than one of the following prognostic factors: *CD4 below 100/µl, *history of opportunistic infection, *Karnofsky index below 60 percent or ECOG over 2)
• Written inform consent to participate

Exclusion Criteria:

• Active viral hepatitis
• Pregnancy