We report the case of a twenty-one-year old woman using oral contraceptives who underwent partial hepatectomy for fibrolamellar carcinoma. Anti-HBs and anti-HBc antibodies were present in the serum and chronic hepatitis was associated with the carcinoma. Study of the tumor with DNA hybridization techniques showed the presence of integrated DNA sequences of the hepatitis B virus in the tumor cells. This observation underlines the possible interactions of different factors in hepatic carcinogenesis, and suggests that estrogens may possibly act as a cocarcinogenic factor associated with viral infection.