A papilloma on the penis of a colobus monkey was found to contain papilloma-virus group specific antigens by immunohistochemical analysis and virus-like particles in the nuclei of epithelial cells by transmission electron microscopy. In low-stringency Southern blot hybridizations, DNA from the lesion annealed with human papillomavirus 11 DNA, but not with the DNAs of 13 other papillomaviruses. Using human papillomavirus 11 DNA as a probe in Southern blot hybridizations, DNA from the penile papilloma was shown to contain a supercoiled DNA approximately 8 kilobases in size. This represents the first demonstration of a papillomavirus-associated venereal lesion in a nonhuman primate.