The daily dietary consumption of refined sugar was studied in four equal-sized groups of 30 patients with Crohn's disease, ulcerative colitis (UC), irritable bowel syndrome (IBS), or minor orthopedic conditions. The latter group was matched for sex and age with the Crohn's disease group. The Crohn's disease patients consumed significantly more refined sugar (88.9 +/- 50.7 (SD) g/day) than the controls (64.3 +/- 45.6 g/day), the UC patients (64.3 +/- 38.7), or the IBS patients (59.9 +/- 33.3). Fifteen patients with Crohn's disease interviewed within 6 months of diagnosis consumed similar amounts of sugar (69.9 +/- 43.9) to those of the subjects in the other three groups. Fifteen other patients with Crohn's disease studied 7-36 months after diagnosis consumed significantly more refined sugar (107.9 +/- 41.2). These results indicate that the high sugar consumption in Crohn's disease is a secondary phenomenon without etiologic importance.