Albeit remaining a controversial issue, it has become increasingly recognised that psychological stress has a major impact on gut mucosal function and affects the course of gastrointestinal disorders. Research during the last decade has shown that stress causes barrier dysfunction of the gastrointestinal mucosa by mechanisms that mainly involve neuropeptides and mast cells. Moreover, accumulating evidence implicates increased permeability as a pathogenic factor in gastroesophageal reflux disease (GORD). Recent data demonstrating that psychological stress may induce a permeability defect in stratified epithelia, including the oesophagus, shed new light on the pathophysiological events leading to heartburn and GORD.