The evidence that duodenal ulcer is a psychosomatic disorder is reviewed. A variety of both experimental stressors and differing states of emotional arousal (anxiety and anger in particular) are associated with increased acid and pepsin secretion. Furthermore, chronic life stressors predispose to duodenal ulcer, presumably by way of symptomatic anxiety or depression, while poor social support may comprise another risk factor. Subjects with high levels of trait anxiety or neuroticism are more prone to stress-induced anxiety and its physiological consequences. There is minimal acceptable evidence to support more specific personality-related theories, including Type A behaviour, alexithymia or the earlier psycho-analytic theories of Alexander. Nonetheless, it is concluded that Alexander's inclusion of duodenal ulcer as one of a handful of classic psychosomatic disorders has been confirmed. Since some 40% of duodenal ulcer patients relapse in the first year after medical treatment, there may be some role for psychological treatments (especially in the domain of stress/anxiety management) for those patients who relapse and have co-existing high state or trait anxiety or exposure to chronic stressors.