It is known that proliferation and apoptosis are closely related phenomena in liver cancer cells. In this study, using surgical specimens from 42 patients with hepatocellular carcinoma (HCC), we investigated the expression and localization of Bcl-xL, an antiapoptosis-related protein of the Bcl-2 family. Using Western blotting, Bcl-xL expression was detected in both cancerous and non-cancerous specimens from all of the HCC patients, and elevated Bcl-xL levels were found in cancerous specimens from two thirds of the patients. In normal human liver specimens, Bcl-xL was found mainly in the cytoplasm of hepatocytes, although it was also found in the cytoplasm of bile duct cells in Glisson's capsule by immunohistochemical staining. To the best of our knowledge, this is the first report of Bcl-xL overexpression and localization in HCC specimens. Bcl-xL was found not only in the cytoplasm of HCC cells, but also in the nuclei of some HCC cells, suggesting that Bcl-xL is involved in the progression of HCC cells in vivo.