To identify potentially remediable abnormalities in Crohn disease, 63 patients had evaluations performed for anemia, electrolyte deficiencies, defects of carbohydrate, fat, nitrogen, and vitamin B12 absorption, and jejunal bacterial overgrowth. Ninety percent of the group had two or more potentially correctable defects. More than 50% had anemia associated with iron or folate deficiency of vitamin B12 malabsorption; 33% had low levels of serum sodium, potassium, calcium, or magnesium either singly or in combination; 22% had lactose intolerance, fat malabsorption was persent in 31%; 75% had evidence of disturbed protein metabolism; and bacterial overgrowth of the upper part of the small bowel was identified in 30% of 47 patients.