The evolution of gastric moderate and severe dysplasia was examined in a prospective multicenter study. One-hundred-and-nine of 141 patients with the endoscopic-bioptic diagnosis of moderate or severe dysplasia had an adequate follow-up and were included into the study. After revision of the initial slides by a gastrointestinal pathologist, 57 patients whose lesions did not meet the histological criteria for dysplasia were excluded, being reclassified as hyperplastic or metaplastic lesions (group 2). The 52 patients with confirmed moderate or severe dysplasia (group 1) were followed up for at least six months or underwent surgery for confirmed dysplasia or cancer. Thirty-two cancers were found in group 1 (33% in patients with moderate and 81% in patients with severe dysplasia). Among them, about half (n = 17) were early gastric cancers. Neither severe dysplasia nor cancer were found during the follow-up in group 2. Mean follow-up time was 13 months in group 1 and 16 months in group 2. Our results indicate that: 1) Confirmed moderate dysplasia shows a high risk of cancer development and requires strict bioptic follow-up; 2) Surgery is indicated in confirmed severe gastric dysplasia seen in the early detection of gastric cancer.