Inclusion Criteria:

1. HIV seropositivity
2. Biopsy diagnosis of a CD20+ diffuse large B-cell lymphoma diagnosed according to the World Health Organization (WHO) classification
3. Advanced disease (stage III or IV according to Ann Arbor staging system)
4. Age 18 years or older.

Exclusion Criteria

1. Performance status ≥3 according to ECOG (Zubrod) scale (see Appendix I)
2. Known primary central nervous system lymphoma or parenchymal brain involvement with lymphoma
3. Non-measurable disease by physical examination or radiographic evaluation
4. Absolute CD4+ cell count <50 cells/mm3 within 3 months prior to trial initiation
5. Inadequate hepatic function (total bilirubin ≥35 µmol/L, alkaline phosphatase ≥2 xUL normal, AST/ALT ≥2 xUL normal) unless directly attributable to lymphoma or known Hepatitis B or C co-infection.
6. Inadequate renal function (serum creatinine ≥125µmol/L) unless directly attributable to lymphoma
7. Inadequate haematological function (haemoglobin ≤85 g/L, absolute neutrophil count ≤1000 cells/mm3, platelet count ≤75,000 cells/mm3) unless directly attributable to lymphoma or autoimmune thrombocytopenia.
8. Evidence of left ventricular (LV) dysfunction (ejection fraction ≤ 50%) in patients over the age of 60 or in patients with a prior history of hypertension, congestive heart failure, peripheral vascular disease, cerebrovascular disease, coronary artery disease, or cardiac arrhythmia
9. Pregnant or lactating women who intend to breast-feed during the trial period
10. Men of reproductive potential and women of childbearing potential who are not using or not willing to use effective contraception
11. Known intolerance to the prescribed chemotherapy or antiretroviral drugs
12. Life-expectancy ≤ 3 months
13. Geographically inaccessible for follow-up