Thirty-six patients (27 with ulcerative colitis and 9 with Crohn's disease) completed a prospective controlled therapeutic trial of intravenous hyperalimentation (IVH) and total bowel rest in acute colitis. All patients received prednisone 40 mg/day which was reduced every 3 days or more depending on the response to treatment. The trial was completed either when the prednisone was reduced to 10 mg/day or when the patient came to colectomy. In the control group (5 males, 12 females; mean age 44.7 yr), 6 came to surgery and 11 responded medically in a mean time of 23.7 days. In the IVH group (8 males, 11 females; mean age 37.4 yr) 9 came to surgery and 10 responded medically in a mean time of 21.2 days. The results of this trial show that IVH with total bowel rest has no primary therapeutic effect in acute colitis.