Whether Helicobacter pylori infection alters the risk of ulcer disease in patients receiving nonsteroidal anti-inflammatory drugs (NSAIDs) or low-dose aspirin is one of the most controversial topics in peptic ulcer research. This is an important management issue, particularly in countries where peptic ulcer disease is common and the prevalence of H. pylori infection is high. Current evidence shows that H. pylori infection increases the ulcer risk associated with NSAIDs or low-dose aspirin. Eradication of H. pylori reduces the subsequent risk of endoscopic and complicated ulcers in patients who are about to start long-term NSAIDs. Among patients with H. pylori infection and a history of ulcer bleeding who continue to use low-dose aspirin, 1 week of eradication therapy prevents recurrent ulcer bleeding. Failure of eradication and concomitant use of NSAIDs, however, account for most cases of recurrent bleeding with low-dose aspirin. The apparent protective effect of H. pylori in long-term NSAIDs users reported in some studies was actually the weeding out of susceptible patients who were intolerant to NSAIDs. There is no convincing evidence that eradication of H. pylori has any clinically important adverse effect on the healing and prevention of ulcers in NSAIDs users.