Total parenteral nutrition (TPN) is commonly used in the management of inflammatory bowel disease (IBD). Claims of its effectiveness are conflicting, and most reports have been limited to short-term assessments. We undertook a nonrandomized prospective study of the effects of TPN on the course of IBD in 30 patients whose disease was refractory to medical therapy, 20 with Crohn's disease and 10 with ulcerative colitis. Parameters of nutritional improvement, subjective and objective clinical response during TPN, and long-term outcome were assessed. All but one of the patients gained weight. Seven of the 20 Crohn's patients, including 3 of 4 with fistulas, had no response to TPN. The other 13 had reduction of diarrhea, relief of abdominal pain, and an improved sense of wellbeing during TPN. On long-term follow-up, five of these patients relapsed and required surgery; five remain improved with active disease controlled by medication 2-24 months later, and three are symptom-free and off all medication 20-48 months later. Clinical improvement during TPN was observed in only four of the 10 ulcerative colitis patients; six required colectomy after 9-24 days of TPN. Of the four responders, one relapsed and had colectomy one month later, two continue to have active disease controlled by medication five and 43 months later, and one has been symptom-free and off all medication for over three years. We conclude that TPN is useful adjunctive therapy for IBD patients requiring bowel rest and nutritional repletion. Dramatic clinical improvement occurs in some patients but is unpredictable. © 1980 Digestive Disease Systems, Inc.