A cell line designated as BV9 was established in culture from a transplantable rat stomach cancer, which was originally induced in the glandular stomach of a Wistar rat by p.o. administration of N-methyl-N'-nitro-N-nitrosoguanidine. The monolayer cells, which have been subcultured for more than 35 passages, revealed pleomorphic features. Chromosomal analysis showed hypertetraploidy (mode, 95), and marker chromosomes were present. Cultured cells were injected s.c. into cyclophosphamide-conditioned syngeneic rats and produced tubular adenocarcinomas resembling the original tumor.