We examined 32 cases of surgically resected stomach cancer for the immunohistochemical expression of p53 and c-erB-2 protein and correlated the findings with clinical outcome and established prognostic factors. p53 Was observed in the nuclei of tumor cells in 11 of 32 cases (33%) and c-erbB-2 immunoreactivity was observed in nine of 32 cases (27%). In eight cases both p53 and c-erbB-2 were positive; however, double immunostaining revealed that less than a third of the same tumor cells were positive for both p53 and c-erbB-2 in these cases. The immunohistochemical localization patterns of p53 and c-erbB-2 were not related to the histopathologic differentiation of the carcinoma cells. No correlation was observed between expression of p53 and/or c-erbB-2 and the clinical outcome and established prognostic factors, including clinical stage and histologic types of the tumor examined. These results indicate that abnormalities of p53 and c-erbB-2 may not play major roles in the biologic behavior of human stomach cancer and that abnormalities in p53 and c-erbB-2 do not necessarily occur simultaneously in the development of stomach cancer.