SUMMARY Gastric carcinoma was detected nine, 10, 18, and 21 years after the biopsy diagnosis of atrophic gastritis in four patients of a group of 40. The gastritis was presumed to be of the simple type. Tests of vitamin B,2 absorption in three patients gave normal results, no gastric autoantibodies were detected in the two patients tested, in all patients histological examination of the gastrectomy specimens revealed a multifocal gastritis differing from the diffuse gastritis of pernicious anaemia and in three patients the gastritis affected the antrum, which is unusual in pernicious anaemia.The 10 % incidence of gastric carcinoma in 40 patients with simple atrophic gastritis followed for a mean period of 15 years is equivalent to that previously described in pernicious anaemia. However, in view of the relative incidence of atrophic gastritis with and without pernicious anaemia in the general adult population, it emerges that atrophic gastritis without pernicious anaemia is numerically the more important precursor of gastric carcinoma.