Abstract: Objective To investigate the relationship between ischemic stroke associated pneumonia (SAP) and intestinal mucosal barrier dysfunction after stroke, and evaluate the predictive value of serum diamine oxidase (DAO) and d-lactate (D-Lac) levels for SAP. Methods A total of 80 patients who originally presented acute ischemic stroke from June 2018 to October 2018 and admitted in the Affiliated Hospital of Xuzhou Medical University were selected as subjects. According to the presence of SAP within 48 h to 7 d after onset of ischemic stroke, the patients were divided into two groups: a SAP group (n=37) and a non-SAP group (n=43). Peripheral venous blood samples were collected on Days 1, 2, and 7 after onset, and the activity of serum DAO and D-Lac concentration were determined. The general information, serum DAO and D-Lac levels were compared between the two groups. The predictive value of DAO and D-Lac to SAP were evaluated. Results Compared with the non-SAP group, the SAP group showed remarkable differences in age, diabetes history, stroke area, disturbance of consciousness, dysphagia, mechanical ventilation, nasogastric nutrition, GCS score and NIHSS score (P<0.05). Significant increases were found in the SAP group as to the activity of serum DAO on Days 1 and 2 after ischemic stroke, and the level of serum D-Lac at each time point after ischemic stroke (P<0.05). The activity of DAO and level of D-Lac were statistically different in the same group at different time points (P<0.001). Moreover, the activity of serum DAO decreased but the level of serum D-Lac increased, along with the time. The ROC curve showed that the area under the curve (AUC) of serum DAO on Days 1 and 2 after stroke was 0.711 and 0.687, respectively, with a specificity of 82.9% and 86.9%, and a sensitivity of 61.9% and 42.9%. The AUC of D-Lac was 0.845 and 0.736, respectively, with a specificity of 82.9% and 72.2%, and a sensitivity of 83.3% and 66.7%. Conclusions The occurrence of SAP in patients with ischemic stroke is related to the damage of intestinal mucosal barrier. Serum DAO activity and D-Lac level are of predictive value for SAP, where D-Lac level is the most effective on Day 1 after stroke.