Abstract: 250pg/ml of PNNG in 0. 4% tween 80 solution was taken by Wistar rats ad lib. When the total amount of PNNG taken by a rat reached 2,500mg or more,gastric micro adenocarcinomas of the rats were found. The induction time was shortened to 370 days. The stomachs of the 48 autopsy rats were examined under microscope and electron microscope. It was found that in a case of early gastric micro adenocarcinoma two separate gastric glands showed malignant changes in the tubular epithe-lial cells. This was in favor of the multi-centric theory of gastric adeno-carcinoma.