There are to date seven recognized human papillomaviruses (HPV) and four bovine papillomaviruses (BPV). The human papillomaviruses are each associated with distinct clinical entities varying from common warts to condyloma accuminata and laryngeal papillomatosis. The bovine papillomaviruses cause fibropapillomas and alimentary tract papillomas in their natural host and induce tumors in hamsters when injected. None of these viruses can be propagated in tissue culture. We have molecularly cloned the genomes of several human papillomaviruses.