AbstractRecent results show that polymorphisms of programmed death ligand 1 (PD‐L1, also known as CD274 or B7‐H1) might be used as a possible marker for effectiveness of chemotherapy and cancer risk. However, the effect of PD‐L1 gene variations on PD‐L1 expression remain unclear. Given the post‐transcriptional machinery in tumor PD‐L1 expression, we investigated single nucleotide polymorphisms (SNPs) in the 3′‐untranslated region (3′‐UTR) of the PD‐L1 gene, rs4143815 and rs4742098, using formalin‐fixed paraffin‐embedded sections of 154 patients with non‐small cell lung cancers (NSCLCs). In rs4143815, the GG genotype showed significant association with PD‐L1 expression (P = 0.032). In rs4742098, the AA genotype was significantly associated with histology and PD‐L1 expression (P = 0.022 and P = 0.008, respectively). In multivariate logistic regression analysis, the AA genotype in rs4742098 was correlated with PD‐L1 expression (odds ratio 0.408, P = 0.048). Interestingly, approximately 10% of the NSCLC cases showed somatic mutation when we compared genotypes of these SNPs between NSCLC tissues and non‐tumor tissues from the same patients. In addition, cases with somatic mutation showed higher levels of PD‐L1 expression than cases with germline mutation in rs4143815 GG. In conclusion, we demonstrated that the rs4143815 and rs4742098 SNPs in the 3′‐UTR of PD‐L1 were associated with tumor PD‐L1 expression in NSCLCs.