Objective To investigate the prevalence and the risk factors of gastroduodenal damages induced by nonsteroidal anti-inflammatory drugs (NSAIDs). Methods One hundred and eighty-four patients who were prescribed NSA1Ds for long time in rheumatology and cardiovascular clinics were enrolled. Clinical data such as age, sex, medication history and body mass index were recorded. The lesions were estimated by endoscopy and the specimens were tested for Helicobacter pylori (H. pylori) infection. Results Peptic ulcer was found in 63 (34. 24%) patients including gastric ulcer in 22, duodenal ulcer in 34 and compound ulcer in 7. The endoscopic examination showed that 57 out of 121 patients without peptic ulcer had ≥3 erosive lesions. Logistic regression analysis revealed that H. pylori infection was important risk factor that induced the peptic ulcer in those who were taking NSAIDs for long time (OR = 13. 86, 95% CI: 6. 53 ～ 29. 43). The incidence of gastroduodenal damage was similar in patients taking NSAIDs and low dose aspirin (OR =0.45,95CI:0.16～ 1.28). Conclusions NSAIDs may cause gastroduodenal damages in long-term users and H. pylori infection was an important risk factor. The effect of low dose aspirin on gastroduodenal damages is as same as NSAIDs.