Programmed death ligand 1 (PD L1) expression can reduce the immune response in both infectious diseases and cancers. We thus examined PD L1 expression in cervical intraepithelial neoplasias (CINs) and cancers since they each reflect infection by human papillomavirus (HPV). PD L1 protein was not evident by immunohistochemistry in histologically normal cervical epithelia (0/55) even when adjacent to CIN or cancer. PD L1 expression was much increased in CINs (20/21=95%) and cervical squamous cell cancer (56/70=80%) and localized to the dysplastic/neoplastic squamous cells and mononuclear cells, respectively. There was also a significant increase (each P<0.001) in PD L1 detection in mononuclear cells when comparing cervical squamous cell cancers to endometrial (22/115=19%) and ovarian adenocarcinomas (5/40=13%). Co-expression analyses showed that the primary inflammatory cell that contained PD L1 was the CD8+ lymphocyte that strongly concentrated around the dysplastic CIN cells and nests of invasive squamous cancer cells. These data show that PD L1 is a solid biomarker of productive HPV infection of the cervix and that it is significantly upregulated in both the carcinoma and surrounding inflammatory cells in cervical cancer when compared with other gynecologic malignancies. This suggests that anti-PD L1 therapy may have a role in the treatment of cervical cancer.