HPVs (Human Papilloma Viruses) are small DNA "epitheliotropic" viruses, implicated in cervical carcinogenesis, particularly the "high-oncogenic-risk" types HPV-16 and HPV-18. Data concerning oral carcinogenesis are however, contradictory. We examined the presence of HPV and subsequently HPV-16 and HPV-18 in 102 specimens of paraffin-embedded oral tissue blocks--81 oral squamous cell carcinomas and 21 oral hyperplasias--using PCR technique followed by agarose gel electrophoresis. Our results demonstrated that 49% (50/102) of the samples were HPV positive. Subsequent analysis of HPV positive lesions revealed 22% positivity for HPV-16 and 44% for HPV-18. HPV-18 was detected only in carcinomas, while HPV-16 was more abundant in papillomatous hyperplasias and in a small percentage of carcinomas. These findings may probably indicate a contributing role for HPV-18 as a potent co-carcinogen in oral epithelial carcinogenesis in the Greek population.