Background/Aims: Early gastric cancer (EGC) has a relatively long natural course compared to advanced gastric cancer (AGC). But, few studies about the natural course of EGC are currently available in the literature. In this study we investigated the natural course of EGC in patients who did not receive any treatment. Methods: All patients diagnosed with gastric cancer on endoscopy at Kosin University Gospel Hospital between January 2001 and December 2010 were reviewed. Those among them who had EGC and did not receive any treatment were enrolled, and an analysis was performed. Results: Twenty seven patients were enrolled. Nine of the enrolled patients were women and the median age was 73 years (range, 38-95). Initial endoscopic findings revealed 11 cases of protruded type, 16 cases of flat and depressed type. Histopathologic analysis indicated that there were 14 cases of well and moderately differentiated adenocarcinoma, 6 cases of poorly differentiated adenocarcinoma and signet ring cell carcinoma. Twelve patients underwent follow-up endoscopy and three of them developed AGC within a mean of 9.6 months (range, 5-12 months). Overall median survival time was 40 months and the 5-year survival rate was 45%. Conclusions: Although there were some differences in EGC progression, patients who did not receive any treatment progressed eventually. We were unable to identify specific factors predictive of median survival time in these patients.