Epithelial cell lines (9) were isolated from glandular stomach cells of fetal and suckling JAR-2 rats after the elimination of mesenchymal cells by mechanical and colonial isolation methods. These cells proliferated continuously in a typical pavement-like arrangement. In early cultures a part of focal monolayers of small epithelial cells died simultaneously (contact death). The cells of 3 lines (RGS-2,RGS-5 and RGS-8) formed hemicysts when incubated for several weeks without subcultivation. Addition of But2cAMP [dibutyrly cyclic AMP] and theophilline to culture medium enhanced hemicyst formation by RGS-8 cells. Some evidence suggested that these 3 lines originated from mucous epithelium of rat glandular stomach. These epithelial cell lines would be useful in the study of chemical carcinogenesis in culture.