The number of folds and lumen diameter of the proximal jejunum and distal ileum were retrospectively measured in 40 double-contrast small bowel enteroclysis studies of patients with a biopsy-proven diagnosis of adult celiac disease (ACD) and in 46 healthy control subjects. For both parameters an inverse radiographic pattern was found in celiacs compared to control subjects, in whom the number of folds and lumen calibers are physiologically greater in proximal jejunum than in the distal ileum. Mean differences in the jejuno-ileal number of folds (-7.1) and lumen calibers (-1.3 cm.) were in fact negative in ACD patients, in whom the values of both the parameters are less in the proximal jejunum than in the distal ileum. Particularly, the sign of "reversal of jejuno-ileal caliber" was both sensitive and specific for diagnosis of ACD in this retrospective series. Double-contrast small bowel enteroclysis can play an important role in excluding or confirming the presence of ACD, provided that an assessment of reproducibility and a prospective re-evaluation of operative characteristics of such radiographic signs are performed.