Methods have been established to produce gastric cancer in rats and dogs by administration of N-methyl-N'-nitro-N-nitrosoguanidine or of the ethyl derivate. The agent is administered in drinking water or by a pellet diet soaked in the carcinogen. Histologically well differentiated and poorly differentiated types of adenocarcinoma and signet-ring cell tumors are induced in several months with greath reliability. Metastases were observed in both rats and dogs with gastric carcinoma. The carcinogenic effect could be enhanced by surface active agents, sodium chloride, iodoacetamide, insertion of plastic beads into the stomach and gastroenteroanastomosis. Follow-up studies by radiologic, endoscopic and bioptic examinations are possible in the dog. There are similarities in these experimental tumors to those in man and thus they provide means for the investigation of histogenesis, prevention, and chemotherapy of gastric cancer. An adenocarcinoma of the glandular stomach of a Wistar rat was successively transplanted to new born rats of the same strain.