Summary Regional enteritis is a nonspecific, granulomatous, inflammatory condition, of unknown etiology. It affects the terminal ileum and to a less extent the colon, the proximal ileum, jejunum, duodenum and stomach. Whether it is actually increasing in frequency is not known. Certainly it is being diagnosed and recognized more frequently at present. It is a common source of chronic invalidism and must be considered in the differential diagnosis of many acute and chronic abdominal conditions. Because of its varied manifestations, it can simulate many systemic and functional entities. Thus, it is important for general practitioners, internists and surgeons. All attempts to implicate a specific bacteria or virus as an etiologic agent have been unsuccessful. It has recently been suggested that the initial inflammatory process is an autoimmune reaction in a hypersensitized bowel—but proof of this is lacking. There is no specific medical treatment and in many patients the disease progresses to a point at which operation must be resorted to in order to preserve life, to relieve severe symptoms or to avoid chronic invalidism. The most common operative indication is small bowel obstruction. Internal and external fistulas are also common complications. The surgical treatment of choice today is resection of the disease process, conserving as much healthy colon and small intestine as possible. The mortality rate for the surgical treatment is low but the recurrence rate remains high. Approximately 25% of these patients will require further surgical procedures. On the other hand, all but a few patients can be restored to health by a combination of surgical and medical treatment. None should be regarded as hopeless.