The apoptotic machinery has been intensively investigated, and interleukin-1-beta-converting enzyme (ICE) and its homologs directly mediate apoptosis by means of their unique protease activity. Fas/Apo1 (CD95), a member of the TNF-receptor family, mediates apoptosis by binding to its ligand, which is mainly expressed on lymphocytes. Here, we investigated the expression and function of both molecules in renal-cell cancer (RCC). The expression of Fas was examined in 6 RCC cell lines by immunoblotting and all of them expressed Fas. ICE and CPP32/YAMA were also identified among the cell lines. We earlier examined ACHN cells expressing low levels of BCL-2, as well as KRC/Y cells with high levels of BCL-2. Here, we found that the anti-Fas monoclonal antibody, CH-11, induced apoptosis in a dose-dependent fashion more remarkably in ACHN cells. Pre-incubation with the tetrapeptide YVAD-chloromethyl-ketone or DEVD-aldehyde inhibited Fas-mediated apoptosis. These findings suggest that, in RCC, apoptosis is induced by lymphocytes bearing Fas-L, and that it is achieved through the proteolytic action of CPP32/YAMA and/or ICE, or another member of the ICE/ced-3 protease family.