Aspirin is the main actor in primary and secondary preventive treatments in cardiovascular diseases. However, it has several side effects including gastrointestinal toxicity (peptic ulcer formation, bleeding). Although lower doses are relatively safe, we should keep in mind that even the lowest dose may cause gastrointestinal bleeding. Gastrointestinal toxicity profile does not differ between conventional and enteric-coated aspirin use. In patients who have cardiovascular disease but are at high risk for gastrointestinal bleeding, eradication of Helicobacter pylori infection and concurrent proton pump inhibitor therapy may help to reduce the risk of gastrointestinal toxicity.