SUMMARYGastroenterologists believe that non‐steroidal anti‐inflammatory drugs (NSAIDs) cause dyspepsia, may cause ulcers to developde novoand cause ulcer bleeding and perforation. Regulatory authorities are aware that NSAID‐associated adverse events are reported more often than for any other drug class, and that gastrointestinal events are most common and often serious. A case‐control study in the UK indicates that those who use NSAIDs may be between two and four times as liable to gastrointestinal bleeding and probably perforation as non‐users, particularly if elderly. It has further been suggested that the chances of dying of ulcer complications are very high in NSAID users. By contrast, studies in the USA conducted prospectively and post‐marketing surveillance in the UK have appeared to show little risk. Differences may be partially, if not completely, explained by the variable methodologies employed. Dispute also exists about the rank order and significance of toxic effects among the var