In 23 patients with dermatitis herpetiformic (DH) and five patients with linear-IgA bullous dermatosis (BD) we evaluated the occurrence of histologic jejunal changes and small-bowel function abnormalities. None of the patients showed clinical signs or symptoms of malabsorption. Morphological jejunal changes consistent with gluten-sensitive enteropathy were found in 82% of DH patients and in 60% of DD patients. However, DD patients showed only mild jejunal histologic abnormalities, whereas more severe jejunal lesions were found in most patients with DH. Functional tests showed a rough correlation with the severity of the jejunal lesions, being almost completely normal in BD patients and DH patients with mild intestinal damage, whereas most of DH patients with subtotal or total villous atrophy showed abnormal d-xylose tests and folic acid assays. Lactose tolerance tests (H2breath test and blood glucose after oral lactose load) showed no correlation with the degree of jejunal damage.