PNNG, the propyl derivative of MNNG, was administered to Wistar rats by a concentration of 59.5 micrograms/ml in the drinking water for 4, 8, and 12 months and the rats were killed in the 15th month. Intestinal metaplasia was induced in the glandular stomachs of 25%, 75%, and 83% of the rats treated with PNNG for 4, 8, and 12 months, respectively. Metaplastic glands were found in the pyloric region, especially near the pyloric ring. These glands contained goblet cells and columnar cells with striated borders. No tumors were found in the stomach of rats after 4-months treatment, but adenomas were found after 8-months treatment, and both adenomas and adenocarcinomas after 12-months treatment.