A premalignant condition with high risk of gastric cancer is the basis for prophylactic gastric surgery. The germline mutation carrier in the E-cadherin gene has a lifetime risk of 70-80% for diffuse-type gastric cancer, and high-grade intraepithelial neoplasia has a 60-70% gastric cancer risk. Other premalignant conditions such as HNPCC syndrome (5% gastric cancer) and low-grade intraepithelial neoplasia (10% risk) are moderate risk factors for developing gastric cancer. They do not justify prophylactic surgery, but surveillance is required. In case high-grade intraepithelial neoplasia or early gastric cancer is detected, an option is extended radicality with total gastrectomy instead of subtotal gastric resection. Positive family history and early-onset of gastric cancer are risk factors to consider when discussing prophylactic gastrectomy or extended radicality.