The experimental induction of gastric cancer was studied in four dogs given oral administration of N-ethyl-N'-nitro-N-nitrosoguanidine (ENNG) in solution. Esophageal cancer with the regional lymph node metastasis was found in one dog at autopsy, with concomitantly existing gastric cancer. This dog, which ingested a total amount of about 38 g of ENNG, died of weakness on the 513th experimental day. Three remaining dogs are still living and under observation.