Nonsteroidal anti-inflammatory agents (NSAIDs) are among the most widely prescribed drugs worldwide. In France, about 25% of individuals aged 40 years or older are treated with NSAIDs at least one week in the year. Although the therapeutic benefits of these drugs are substantial, their use is limited by their gastroduodenal toxicity. Dyspepsia occurs in about 30% of patients receiving NSAIDs, an approximately two-fold enhancement of risk compared with control subjects. Asymptomatic endoscopic lesions are observed in 20 to 80% of patients, depending on population characteristics, individual NSAIDs and definitions of endoscopic lesions. The risk of symptomatic ulcer, complicated ulcer (haemorrhage, perforation, stenosis) and death related to ulcer complication is multiplied by 4 in patients treated with NSAIDs. Established risk factors for NSAID-induced gastroduodenal complications are age, ulcer history, heavy alcohol consumption, individual NSAIDs, dose, association with corticoid or aspirin or anticoagulants (ulcer haemorrhage) while the role of treatment duration and Helicobacter pylori infection are controversial.