Objective:To investigate the expression of programmed death ligand 1 (PD-L1) in rectal cancer tissues and the correlation of PD-L1 expression with clinicopathological characteristics and overall survival of patients.Methods:The clinical data of 200 newly treated rectal cancer patients in Shanxi Provincial Cancer Hospital from January 2014 to December 2015 were retrospectively analyzed. The expression of PD-L1 in rectal cancer tissues was detected by immunohistochemistry. The correlations of PD-L1 expression with gender, age, tumor T stage, lymph node metastasis, tumor differentiation, histological type, tumor TNM stage, neutrophil-to-lymphocyte ratio (NLR) and overall survival of patients were analyzed.Results:The positive expression rate of PD-L1 was 24% (48/200). The positive expression rate of PD-L1 was high in patients with lymph node metastasis and high NLR (≥ 3.5) (both P < 0.05). The 5-year overall survival rate in PD-L1-positive group was 42%, and the PD-L1-negative group was 59%, and the difference between the two groups was statistically significant ( P < 0.05). The results of multivariate analysis showed that lymph node metastasis ( HR = 3.456, 95% CI 2.148-5.556, P < 0.01), NLR ≥ 3.5 ( HR = 1.871, 95% CI 1.169-2.996, P = 0.009), and PD-L1-positive expression ( HR = 2.187, 95% CI 1.373-3.484, P = 0.001) were independent adverse influencing factors for the overall survival of rectal cancer patients. Conclusion:PD-L1 is highly expressed in rectal cancer tissues, and the positive expression of PD-L1 is associated with poor overall survival of patients.