OBJECTIVE The aim of this study was to analyze the characteristics of patients diagnosed with gastric adenocarcinoma without the presence of symptoms and to evaluate the usefulness of screening programs for gastric cancer in Korea. METHODS We retrospectively analyzed the characteristics of 1277 gastric adenocarcinoma patients at Seoul National University Hospital (SNUH) (665 in 1996; 612 in 2001) by dividing them into two groups according to the presence or absence of symptoms (symptomatic group vs asymptomatic group). RESULTS The proportion of asymptomatic patients increased from 1996 (4.7%) to 2001 (17.2%) (P < 0.001). Gastroscopy was the most commonly used screening tool (77.4% in 1996, 95.2% in 2001). The proportion of early gastric cancer (EGC) in the asymptomatic group was higher than in the symptomatic group (74.2% vs 25.9% in 1996, 78.1% vs 35.7% in 2001) (P < 0.001). The curative operation rate was significantly higher in the asymptomatic group. The asymptomatic group had a higher 5-year survival rate (87.7%) than the symptomatic group (51.6%) (P < 0.01). Complementary data from a screening program at the SNUH showed that 19 gastric cancer cases (0.76%) were detected out of 2501 endoscopic examinations; of these, 78.9% (15/19) were early gastric cancer cases, which is in agreement with our results. CONCLUSIONS Patients with asymptomatic gastric adenocarcinoma had fewer advanced lesions, a greater chance for curative operation and a higher survival rate than symptomatic patients. An increase in the number of asymptomatic patients contributed to the increase in overall EGC from 1996 to 2001. These results seemed to support the usefulness of gastroscopy as a screening test for gastric cancer in Korea, where the incidence of gastric cancer is high.