Enteric-coated potassium chloride is responsible for a striking increase in ulcerative lesions of the small intestine. Pathologically these lesions are venous infarctions of varying severity; patients present with obstruction or signs of perforation, or both, and rarely with bleeding. Roentgenologic studies demonstrate partial intestinal obstruction. Careful investigation of drug ingestion is essential in making the diagnosis. Based on clinical, experimental, and pathological studies, aggressive surgical therapy is recommended. Because irreversible damage may have occurred by the time symptoms appear, medications containing enteric-coated potassium should be limited to patients who require thiazides and whose potassium requirements cannot be met by dietary means.