BACKGROUND AND AIM The recommended interval of endoscopic screening for gastric cancer (GC) in a general population is 2 years in Korea. However, it has not been determined whether endoscopic screening with a shorter interval is beneficial, especially for high-risk groups. METHODS A total of 415 patients with GC were categorized according to whether they had (vigilant screening group) or not (non-vigilant screening group) undergone endoscopic screening within 1 year before being diagnosed with GC. Clinicopathologic GC characteristics of the two groups were compared. Next, the same analyses were conducted in subgroups of patients with high risk for GC including males, current smokers, first-degree relatives of GC; and patients with Helicobacter pylori infection, gastric atrophy, or intestinal metaplasia (IM). RESULTS The proportion of vigilant screening patients was 36.1%. Early gastric cancer (EGC) was more frequently observed in the vigilant screening group than the non-vigilant screening group (62.7% vs 49.4%, P = 0.009). In the high-risk factor analyses, EGC was more frequently detected among patients with severe IM in the vigilant screening group than the non-vigilant screening group (66.7% vs 35.5%, P = 0.047). In addition, more patients in the vigilant screening group had undergone endoscopic submucosal dissection (ESD; 26.7% vs 0%, P = 0.008) and had stage I (84.6% vs 41.7%, P = 0.012) than in the non-vigilant screening group. CONCLUSIONS Endoscopic screening for GC at 1-year intervals would be beneficial for patients with severe IM in South Korea; this method could detect EGC for which the curative modality would be ESD.