Resumo: O papilomavirus humano (HPV) tem sido associado ao desenvolvimento do cancer de cabeca e pescoco. Entretanto, seu papel na carcinogenese bucal nao e bem definido. O proposito deste estudo foi investigar a prevalencia do HPV em carcinoma epidermoide de assoalho bucal e correlaciona-la com variaveis clinico-patologicas e fatores de risco, bem como verificar sua influencia na sobrevida dos pacientes estudados. A presenca do HPV foi avaliada atraves da nested PCR (nPCR) (GP5+/GP6+ e MY11/MY09) em 29 amostras parafinadas de carcinoma epidermoide de assoalho bucal. O virus foi detectado em 17.2% (5 de 29) das amostras estudadas, tendo maior prevalencia em lesoes de pacientes naotabagistas com mais de 60 anos de idade. Das amostras positivas para o HPV, 100% apresentaram-se em pacientes do sexo masculino com lesoes classificadas clinicamente em estagio III ou IV, geralmente com o diagnostico histologico de carcinoma epidermoide moderadamente diferenciado. No entanto, nao houve significancia estatistica entre as variaveis analisadas, incluindo a sobrevida. A baixa prevalencia do HPV sugere que esse virus nao participa isoladamente no desenvolvimento dos carcinomas epidermoides de assoalho bucal. / Abstract: The human papillomavirus (HPV) has been associated with the development of head and neck cancers. However, its role in oral carcinogenesis is not well defined. The aim of this study was to investigate the prevalence of HPV in mouth floor squamous cell carcinoma and correlate its presence with clinicopathologic variables and risk factors, as well as to verify its influence in the patients'survival. The HPV presence was evaluated by nested PCR (nPCR) (GP5+/GP6+ and MY11/MY09) in 29 paraffin-embedded specimens of mouth floor squamous cell carcinoma. HPV DNA was detected in 17.2% (5 of 29) of the specimens and its higher prevalence was higher in nonsmoking patients over the age of 60 years. From the HPV-DNA-positive specimens, 100% were detected in men and tumors clinically classified as stage III and IV lesions, being most of them moderately differentiated. However, no statistically significant difference was observed among the analyzed variables, including patients' survival. The low incidence of HPV DNA suggests that this virus does not participate isolatedly in the development of mouth floor squamous cell carcinoma. / Orientador: Glauco Issamu Miyahara / Coorientador: José Fernando Garcia / Banca: Marília Heffer Cantisano / Banca: Fábio Daumas Nunes / Mestre