There have been three major advances in the treatment of small bowel fistulas since 1960: irrigation with lactic acid; total or parenteral nutrition; and continuous low flow enteric nutrition. The causation and clinical features of these fistulas are reviewed. The different unfavourable prognostic features are evaluated with reference to a series of 384 cases published by Edelmann et al. (1975). The different methods of treatment, both medical and surgical, are analysed. In spite of the great progress in medical management, surgery retains an important place. The guidelines for this medicosurgical policy are laid down. The mortality of intestinal fistulas was around 60 per cent before 1960 and has now diminished by half. It should be possible to lower it still further to around 10 per cent in future years, by careful application of the methods described.