BACKGROUND/AIMS: Peptic ulcer disease (PUD) is one of the common gastrointestinal diseases, and its medical management has been developed so much that the incidence of its serious complications, such as bleeding and perforation, are declining significantly. Its prevalence in Korea is not definitely decreased, probably due to increasing proportion of elderly patients and their rising usage of non-steroidal anti-inflammatory drugs (NSAIDs) and aspirin. This study was conducted to identify the risk factors for development and recurrence of peptic ulcer disease in Korea. METHODS: From 2003 to 2008, upper gastrointestinal endoscopy and detailed personal questionnaires were performed for patients who visited Department of Gastroenterology at Seoul National University Bundang Hospital. In total, 475 PUD patients and 335 non-ulcer dyspepsia patients were included. The results of questionnaires and repeated upper gastrointestinal endoscopy at initial diagnosis time and follow-up periods were analyzed. RESULTS: Multivariable analysis showed that male, H. pylori infection, NSAIDs use and smoking were risk factors for the development of PUD. The use of proton pump inhibitors (PPIs) and H2 receptor antagonists has significantly reduced the risk of PUD in patients who had taken NSAIDs and/or aspirin. H. pylori infection was found as the only risk factor for the recurrence of PUD. CONCLUSIONS: For the old patients who are taking drugs, such as NSAIDs and aspirin, concomitant use of PPIs or H2 receptor antagonists should be considered to protect from the development of PUD. H. pylori eradication has been confirmed again to be essential for the treatment of PUD patients infected with H. pylori.