Inclusion Criteria:

- Patients with HIV infection diagnosed with DLBCL in any stage (I-IV according to the
Ann Arbor classification) not previously treated for the lymphoma.

- Patients with CD20-positive diffuse large B-cell lymphoma

- Aged from 18 to 70 years old

- Any score of International Prognostic Index. (It is also applicable in patients with
non-Hodgkin lymphoma [NHL] infected with HIV.)

- ECOG performance status 0 to 3

- Written informed consent

- Absolute neutrophil count > 1.5 x 10^9/L.

- Absence of synchronic or non-synchronic neoplasia with the exception of non-melanoma
skin tumors or in situ cervical carcinoma.

- CD4+ lymphocyte count > 100/µL

Exclusion Criteria:

- Patients with diffuse large B cell lymphoma previously treated.

- Patients with primary central nervous system lymphoma.

- Patients with Burkitt or Burkitt-like NHL.

- CD4+ lymphocyte count < 100/µL

- Opportunistic infections or other AIDS-related neoplasias in activity.

- Active drug-addiction.

- Pregnant or lactating women or adults of fertile age who do not use an effective
contraceptive method.

- Patients with serious altered renal function (creatinine > 2.5 x upper limit of
normal [ULN]) or hepatic [bilirubin, ALT or AST > 2.5 x ULN], except if the
investigators suspect that they are caused by the disease.

- Cardiac insufficiency with ejection fraction < 40%

- Patients with serious psychiatric diseases that can interfere with their capacity to
understand the study (including alcoholism or active drug-addiction).

- ECOG > 3

- Patients with a known hypersensitivity to murine proteins or any other component of
the study drugs.