Background: Non-Hodgkin lymphomas (NHL) ranks 10 among the top 15 common cancers worldwide. Diffuse large B-cell lymphoma (DLBCL) is the most common type of the disease. Despite malignancy, DLBCL is curable and sensitive to chemotherapy and radiation therapy. Since first published in 1997, the protocol R-CHOP, a combination of classical chemotherapy CHOP with rituximab, has increased significantly the rate of complete response (CR) and improved overall survival (OS). However, there has been no report of R-CHOP treatment in Hue. Purpose of this research is to evaluate the efficiency of R-CHOP treatment (complete response, progression-free survival) and to describe the toxicities of the protocol. Methods: A retrospective cohort study on 36 patients with diffuse large B-cell lymphoma, CD 20 positive treated with R-CHOP at Hue University Hospital between 2011 and 2016. Results: According to the International prognostic index (IPI), 15 patients (41.7%) had low-risk disease, 14 (38.9%) low-to-intermediate risk, 6 (16.7%) high-to-intermediate risk and 1 (2.7%) high-risk disease. After finishing 8 cycles of therapy, 19 patients (52.8%) achieved complete response. Grade III anemia was observed (13.9%), grade III neutropeniain 4 patients (11.1%) and nausea (5.6%). During a 5-year period, progression – free survival was reported for 66.7% of patients and median for survival time was 3.3 years. Conclusions: The addition of rituximab to the CHOP regimen increases the complete-response rate and prolongs progression -free survival in patients with diffuse large-B-cell lymphoma. The treatment of R-CHOP is well tolerated that the adverse events are mostly reported at grade III and able to control effectively. Key words: diffuse large B-cell, non-hodgkin lymphoma, CD20 positive, CHOP, rituximab