Papillomaviruses (wart viruses) are responsible for the development of benign and malignant epithelial lesions in mammals. More than 60 different types of human papillomaviruses (HPVs) have been isolated to date. Some of them are major candidates as etiologic agents in cervical cancer. DNA from HPV types 16, 18 and 33 is usually found integrated in about 90 percent of genital carcinomas. Integration of the viral DNA into the cellular genome may be an important step towards the development of malignancy. Two early genes of HPVs (E6 y E7) are involved in cellular transformation. Another early gene (E2) participates in gene control by directly binding to conserved DNA motifs in the viral genome. Several protein factors of viral and cellular origin interact with the regulatory region of HPVs and participate in the regulation transcription of oncogenes E6 and E7. Cellular factors, such as immune system and oncogene and anti-oncogene alterations, seem to play an important role in papillomavirus-associated cervical carcinogenesis.