Abstract: OBJECTIVE To explore the risk factors for concurrent pneumonia in the patients with primary gastrointestinal diffuse large B-cell lymphoma (PGI-DLBCL) during CHOP/R-CHOP chemotherapy and observe the influence on prognosis. METHODS The data were collected from 156 patients with PGI-DLBCL who received CHOP or R-CHOP chemotherapy in Zhujiang Hospital, Southern Medical University from Jan. 2012 to Dec. 2025 and were retrospectively analyzed. The patients were divided into the infection group with 57 cases and the non-infection group with 99 cases. Univariate analysis and multivariate logistic regression analysis were performed for the risk factors. In order to ensure an adequate follow-up period, only 131 patients who were diagnosed from Jan. 2012 to Dec. 2023 were chosen for survival analysis. The progression free survival (PFS) and overall survival (OS) were analyzed by means of Kaplan-Meier method and Cox model. RESULTS The proportions of patients with no less than 60 years of age, Lugano phase ranging between ⅡE and Ⅳ, ECOG score no less than 2 points, rise of lactic dehydrogenase and distant lymph node involvement were higher in the infection group than in the non-infection group, and the serum albumin level of the infection group was lower than that of the non-infection group(P＜0.05). Multivariate analysis indicated that ECOG score no less than 2 points, the rise of lactic dehydrogenase and no less than 60 years of age were the independent risk factors for the concurrent pneumonia during the chemotherapy, and the high level of serum albumin was the independent protective factor(P＜0.05). The PFS and OS were lower in the infection group than in the non-infection group(P＜0.001). CONCLUSIONS The no less than 60 years of age, ECOG score no less than 2 points and the rise of lactic dehydrogenase are the independent risk factors for the concurrent pneumonia in the patients with PGI-DLBCL during the chemotherapy, and the high level of serum albumin is the independent protective factor. The concurrent pneumonia during the chemotherapy may remarkably shorten the PFS and OS of the patients.