The developments in enteral feeding for Crohn's disease in the past decade are critically reviewed. The advent of amino acid based chemically defined elemental diets signalled the end of 'total bowel rest' in the management of these patients. Subsequently, controlled clinical trials showed that elemental diets were as effective as corticosteroids in inducing clinical remission in patients with acute exacerbations of Crohn's disease. The later use of peptide based elemental diets, in Crohn's disease produced somewhat conflicting results. The initial uncontrolled studies suggest that polymeric whole protein diets might also be effective in the management of acute exacerbations of the disease, casting in turn doubts concerning the role of dietary antigens in the pathogenesis of Crohn's disease. Results of controlled studies comparing the use of elemental and polymeric diets as primary therapy in Crohn's disease have, however, also produced conflicting results. The results of one recent controlled trial in which the use of polymeric diet was compared with that of corticosteroids does, however, suggest that these diets may have a primary therapeutic effect in Crohn's disease. An analysis of the composition of some of the enteral diets used in different trials suggest that the effectiveness of enteral diets in treating active Crohn's disease might relate more to their fat than nitrogen composition. A hypothesis is proposed that the effectiveness of enteral nutrition in the primary therapy of acute exacerbations of Crohn's disease occurs because the successful diets used contain insufficient precursors for arachidonate derived eicosanoid synthesis.