Recent 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.