Squamous cell carcinomas (SCCs) are common oronasal tumors in nonhuman primates. In this study, 11 cases of oronasal SCC in François' langurs (Trachypithecus francoisi) are described. Five initial cases were discovered on review of the North American François' langur studbook, with a potential familial pattern observed. The studbook was used to identify related individuals, and records were requested for review. Six additional cases were documented, and samples from all cases were submitted for microscopic review, as well as polymerase chain reaction (PCR), immunohistochemistry (IHC), and in situ hybridization (ISH), for generic papillomaviruses and PCR for herpesviruses because either virus may cause SCC in humans and other nonhuman primates. Affected langurs commonly presented with facial swelling or ocular discharge but frequently did not have clinical signs, and carcinomas were diagnosed during routine examinations. Carcinomas were located in the oral or nasal cavities affecting the oral mucosa, tongue, hard palate, or oropharynx. Histologically, SCCs comprised anastomosing cords and nests of neoplastic epithelial cells that differentiated synchronously and asynchronously from peripheral basal type cells to central squamous-type cells and were occasionally oriented around accumulations of necrotic cell debris. Nuclear pleomorphism, anisokaryosis, prominent nucleoli, occasional mitoses, and a scirrhous response were common features. All animals tested negative for both viruses, except two langurs that were positive for generic papillomavirus by PCR, but no papillomavirus was detected by either IHC or ISH. In most cases, affected animals died within 5 mo of diagnosis.