We studied 54 patients who, after small intestinal resection, developed a massive protracted diarrhea with a daily fecal loss greater than 2 kg, status we defined as the "overwhelmed intestine syndrome" (OIS). Median length of residual small bowel was 120 cm, 19 patients had a definitive stoma (jejunostomy, n = 9; colostomy, n = 10), 26 patients had a provisional jejunostomy. Fecal weight greater than 2 kg was related to enteral hyperalimentation (greater than 3,500 Kcal) in 19 patients (induced OIS) and was clearly independent in 16 others who had fecal weight over 3 kg while receiving approximately 2,000 Kcal (obligatory OIS); the last 19 patients had fecal weight between 2 and 3 kg during normoalimentation. Hypocalcemia and hypomagnesemia were common in the three groups. The other complications were seen mostly in patients with obligatory OIS: in those patients, parenteral nutrition was maintained in 9 cases out of 16 (vs. 0 in other groups), nutritional gain was scanty, sodium equilibrium was difficult to obtain in spite of a large sodium intake (380 mmol/day), hospitalization lasted several months and autonomy via the enteral route could not be achieved in 7 out of the 9 patients with definitive short bowel (vs. 0 in other groups). This study shows that the OIS is an unique functional entity. Complications and prognosis are dependent on the obligatory or induced pattern of the syndrome. Only patients with obligatory OIS require definitive home parenteral nutrition.