Abstract: Objective: To evaluate the efficacy and toxicity of combination chemotherapy consisting of Rituximab and CHOP (R- CHOP) in patients with aggressive B- cell non- Hodgkin's lymphoma.Methods: A total of 45 patients with histopathologically proven CD20- positive B- cell non- Hodgkin's lymphoma were randomly assigned into the R- CHOP group (22 patients) and the CHOP group (23 patients). CHOP regimen: Cyclophosphamide 750 mg/m² IV, Vincristine 1.4 mg/m² IV, and Epirubicin 60 mg/m² or Pirarubicin 40 mg/m² IV were administered on the first day of the chemotherapy course; Pred- nisone 100 mg/m 2 was administered orally from the first day to the fifth day; the cycle was repeated every 21 days. R- CHOP regimen: Rituximab 375 mg/mg² was infused on the first day, CHOP was administered starting on the third day. All of the patients have received at least 4 chemotherapy cycles. The therapeutic effect was assessed. All patients were followed up. Results: The complete response rate and overall response rate were 68.2% and 81.8%, respectively, in the R- CHOP group, and 34.8% and 78.3%, respectively, in the CHOP group. The complete response rate in the R- CHOP group was signifi-cantly higher than that in the CHOP group (P<0.05). The 1-, 2- and 3- year survival rates were 90.9%, 81.8%, and 77.3%, respectively, in the R- CHOP group and 91.3%, 69.5%, and 47.8%, respectively, in the CHOP group. The 3- year survival rate was significantly higher in the R- CHOP group than in the CHOP group (P<0.05). The major side effects in the two groups were mild to moderate myelosup-pression and gastrointestinal toxicity, without a significant difference between the two groups (P>0.05).Rituximab infusion- induced adverse effects occurred in 6 patients (27.2%) in the R- CHOP group.Conclusion: Combination chemotherapy including Rituximab and CHOP (R- CHOP) is recommended as the preferred treatment for B- cell non- Hodgkin's lymphoma because it is effective and well- tolerated by the patients.