Abstract Infectious agents represent a major group of risk factors for cancer development and contribute to about 15% of human cancers worldwide. Six viruses and one bacterium, i.e., human papillomavirus (HPV), hepatitis C virus (HCV), hepatitis B virus, human T-lymphotropic virus type I (HTLV-1), Epstein-Barr virus (EBV), Kaposi sarcoma-associated virus (KSHV), and Helicobacter pylori, have been clearly associated with human carcinogenesis. The mucosal high-risk (HR) HPV types are the etiologic factors of cervical cancers and subset of oropharyngeal cancers. In addition, ongoing studies concerning a subgroup of HPV types that infect the skin suggest their involvement, together with ultraviolet radiation (or solar exposure), in the development of nonmelanoma skin cancer (NMSC). Biologic studies have demonstrated that the products of two early genes from the HR HPV types, E6 and E7, play a key role in cancer development. Both viral oncoproteins are able to target several cellular pathways leading to the evasion of the immune surveillance and cellular transformation. These studies also substantially contributed to our understanding of key mechanisms involved in the normal life of the cell. In the last few years, we have performed additional studies on cutaneous and mucosal HPV types and have characterized novel oncogenic viral mechanisms involved in the evasion of the immune response and/or in cellular transformation. A few examples will be presented. Citation Format: Massimo Tommasino. Role of human papillomaviruses in carcinogenesis [abstract]. In: Proceedings of the AACR Special Conference on the Microbiome, Viruses, and Cancer; 2020 Feb 21-24; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2020;80(8 Suppl):Abstract nr IA15.