Eight malnourished patients (5 men and 3 women, mean age 26.5 +/- 0.4 years) suffering from Inflammatory Bowel Disease were prospectively included at admission to study the effect on protein-energy and vitamin status of a specially designed enterally tube fed formula diet. Eighty nine healthy individuals (36 men and 53 women, mean age 34 +/- 2 years) were used as controls. All but one patient were on steroids. The mean caloric supply was 58.2 +/- 2.4 kcal/kg/day with a mean nitrogen content of 0.37 +/- 0.02 gN/kg/day. The mean Total Enteral Nutrition period lasted 20.8 +/- 2.3 days (range 12 to 28 days). Fat- and water-soluble vitamins were studied at admission and after the nutritional period. Likewise both the protein-energy nutritional status and the activity of the disease were evaluated. At admission, plasma levels of folate, biotin, beta-carotene and vitamins A, C and E were significantly lower in patients than in controls. Tocopherol/cholesterol ratio, and vitamin B1, B2, B6, and B12 status were normal. At the end, plasma values of folate, biotin and vitamin C remained unchanged. However, the protein-energy nutritional status and the activity of the disease significantly improved. At admission, 4 out of 8 patients were at risk of developing hypovitaminosis for vitamins A, C, biotin, beta-carotene, and folate. At the end, a similar percentage remained at risk for these vitamins except for vitamin A. The content of some vitamins in the best designed formula diets does not meet the needs for patients with Inflammatory Bowel Disease.