Although dilatation of the jejunum is a well-recognized feature of Crohn's disease there has been no systematic inquiry as to whether this is related simply to distal intestinal obstruction or to other factors such as hypoalbuminemia and mucosal disease. Barium follow-up examinations of 21 patients with Crohn's disease who had serum albumin concentrations of 2.1-4.4 g/dl were reviewed. Fourteen of these patients (67%) had increased mean jejunal width. All patients with direct radiologic evidence of a stricture (six patients) had increased jejunal caliber, but this only accounted for 43% of patients with this abnormality. Of the remaining eight patients, six had hypoalbuminemia, three of whom had serum albumin concentrations less than or around 2.7 g/dl, the previously determined "albumin threshold" for jejunal dilatation. We conclude that increased jejunal caliber in Crohn's disease not only occurs in association with distal intestinal stenosis but also with severe hypoalbuminemia in the absence of obstruction. We were unable to define a cause of jejunal dilatation in 36% of these patients, but propose that functional obstruction due to distal nonstenosing inflammatory disease may be a factor.