The stress ulcer syndrome is described in this thesis. This syndrome is seen in patients admitted to intensive care departments or being treated in field hospitals, in disaster areas, or battle fields. Acute mucosal lesions associated with burns (Curling's ulcers) and central nervous system disorders (Cushing's ulcers) appear to have a different pathophysiology and a different pathology to the real stress ulcers. Peptic ulcers and gastric lesions following use of non-steroidal anti-inflammatory agents also differ from stress ulcers. In chapter 2 the pathology of the stress ulcer is described. The true stress ulcer is usually found in the proximal part of the stomach, although it may rarely be seen in the distal part of the stomach or in the small or large bowel. Erosions are also included in the term stress ulcer. Histologically these are superficial defects which seldom reach the muscularis propria.