Twenty polypoid lesions at gastroenterostomy stomas (the so-called gastritis cystica polyposa-GCP) were endoscopically removed from gastroenterostomy stomas of 16 male and two female patients previously operated for benign lesions. The interval from surgery ranged from 3 to 40 years (mean: 16.2 years). At light microscopy GCP showed 2 histologic patterns: a) with cystic glands limited to the mucosal layer (gastritis cystica superficialis); b) with cystic glands also spreading into the submucosa (gastritis cystica profunda). Atrophy of specific gastric glands, intestinal metaplasia and dysplastic changes also occurred. Local chronic ischemia and inflammatory reaction as a consequence of gastric surgery and suture at gastroenterostomy together with bile reflux were considered responsible for the development of GCP. The sites and the histologic features of GCP resembled those of experimental stomal polyps preceeding carcinoma in rats after partial gastrectomy. The sites of formation, the sex incidence, the interval from previous operation as well as the histologic findings suggest that GCP is a possible precancerous lesion.