BACKGROUND In South Korea, which has a high incidence of gastric cancer, the most common de novo malignancy associated with liver transplantation is gastric cancer. This study sought to identify clinicopathologic characteristics in gastric cancer patients after liver transplantation, and to help manage these cases. MATERIAL AND METHODS We investigated gastric cancer patients after liver transplantation at Asan Medical Center. We analyzed sex, age, cause of liver transplantation, initiating immunosuppressant, pre-transplantation gastric fibroscopy findings, time interval between transplantation and gastric cancer occurrence, follow-up period, existence of gastric cancer screening, Helicobacter pylori infection, family cancer history, gastric cancer treatment, cancer location, size of tumor, macroscopic gross type, WHO histologic type, Lauren's classification, TNM stage, and survival. RESULTS Of 2968 adult liver transplantation patients at our hospital, 19 were diagnosed with gastric cancer. The mean age at the time of gastric cancer diagnosis was 60.2±6.8 (46-71) years and mean time interval between liver transplantation and diagnosis of gastric cancer was 56.0±30.7 (3.20-113) months. Endoscopic submucosal dissection was done for 10 patients, 4 of whom underwent surgical resection. Surgical resection as an initial treatment was done in 8 patients. One patient received chemotherapy first. The standard incidence ratio of gastric cancer in these patients was 1036 per 100 000 persons (95% CI, 623.7-1,619) in men and 318.9 per 100 000 (95% CI, 4.170-1,774) in women. CONCLUSIONS For long-term survival of liver transplant patients, early detection of de novo cancer is necessary. Therefore, annual screening for gastric cancer after liver transplantation is needed, especially in areas where the incidence of gastric cancer is high, such as South Korea.