Prostaglandins play important roles in the gastric mucosal protection and gastric ulcer healing. Non-steroidal anti-inflammatory drugs (NSAIDs) including aspirin are widely used for the aged patients. Administration of the prostaglandin derivatives has been proven to be effective for both prevention and treatment of gastric ulcers associated with NSAIDs, and prostaglandin derivatives are recommended for NSAIDs-induced gastric ulcers by the Japanese guidelines. The important side effects include abdominal pain, flatulence, and diarrhea. Recent advances in diagnostic methods including video capsule endoscopy and balloon endoscopy have enabled us to examine the entire small intestine, and we recognize that prevalence of small intestinal damage in patients taking NSAIDs is high. Prostaglandin derivatives are also useful for these small intestinal damages.