Impaired intestinal function, negatively affecting food digestion and absorption, is called chronic intestinal failure (CIF). The clinical conditions leading to CIF are: fistulas, wide resections and severe damage to small bowel, and chronic intestinal stasis. In the etiology of CIF, the most frequent conditions are: Crohn's disease, postoperative peptic ulcer, mesenteric arteriopathy, radiation enteropathy, acute pancreatitis, jejunoileal diverticulosis and intestinal pseudo-obstruction. The radiologic approach to CIF can aim at: 1) diagnosing the disease and the clinical conditions causing it; 2) morphometric analysis: lesion spread, length of the extant normal small bowel and adaptive changes. Digestive tube radiology has always been considered a fundamental investigation technique to study malabsorption. Double contrast enema has increased the diagnostic capabilities of radiology. Moreover, double contrast enema allows the extraoperative evaluation, in vivo, of a new anatomic feature--i.e., intestinal length--which is a valuable sign for an exhaustive interpretation of CIF, especially of the short bowel syndrome. Thanks to double contrast enema, the changes in the length of mesenteric small bowel can be calculated in vivo (range: 150-430 cm; mean: 291 cm, SD 59). Intestinal length < 150 cm was observed only in resected patients. In 25% of cases, short small bowels were associated with CIF. Such morphometric studies, if applied to clinical practice, may yield valuable information for both diagnosis and prognosis.