AIMS: To assess the risk of gastric carcinoma in patients with histologically verified dysplasia and atrophic gastritis of the stomach. METHODS: One hundred and one patients with mild (n = 84), moderate (n = 14), or severe (n = 3) dysplasia among 359 elderly men who smoked underwent gastroscopy because of low serum pepsinogen. Patients with dysplasia were prospectively followed up for an average of four years with repeated gastroscopies and multiple biopsies. RESULTS: Four of the 84 (4.8%) cases of mild dysplasia had progressed to moderate dysplasia during the follow up. Most of the cases of mild dysplasia had resolved spontaneously. No surgical intervention was required. Three of the 14 (21%) cases of moderate dysplasia had progressed to severe dysplasia, but no carcinomas were observed during follow up. Five moderately dysplastic lesions were removed surgically or endoscopically. In two of these five cases, moderate or severe dysplasia recurred. Two of the three severe dysplasias progressed to carcinoma. CONCLUSIONS: In atrophic gastritis progression of mild and moderate dysplastic lesions seems to be a slow process and is rare in mild dysplasia. However, severe dysplasia is highly predictive of subsequent cancer. It is suggested that a five year follow up interval is sufficient in cases with mild dysplasia and two years in those with moderate dysplasia. Local removal of moderate dysplasia is indicated but does not guarantee that the lesion will not progress. Severe dysplasia requires immediate surgical intervention.