The gastric region of 5-week-old female Wistar rats was irradiated daily with 500 rad of X-ray up to a total of six times. Goblet cells and marker enzymes of the small intestine, such as lactase, trehalase, and maltase, appeared in the pyloric region of the glandular stomach of the rats from the 1st week after final irradiation. Intestinal type crypt without Paneth cells was observed from the 8th week. Sucrase activity appeared from the 26th week. Intestinal metaplasia with Paneth cells appeared from the 71st week. The number of goblet cells, intestinal type crypts, and Paneth cells increased with age. Gastric adenocarcinoma did not develop after irradiation.