Circulating IgA‐class anti‐endomysium antibodies (EmA) can be detected by indirect immunofiuorescence on monkey oesophagus sections. We found EmA in 22 (76%) of 29 patients with dermatitis herpetiformis (DH) on a normal, gluten‐containing diet. The highest frequency (100%) of EmA was observed in patients with sub‐total villous atrophy. IgA‐class antigliadin antibodies (AGA) were found using an ELISA method in 59% of 29 DH patients and in 86% of those with sub‐total villous atrophy. There was a significant correlation between EmA litres and AGA levels in individual patients.

Gluten‐free diet (GFD) treatment caused a rapid decrease in EmA litres; only three of the 12 patients still showed raised EmA after 6–12 months on a GFD and two of these three had failed to adhere to a strict diet. In contrast, no decrease in EmA titres occurred in four patients maintained on a normal diet, and two of the three patients with initially negative EmA developed positive titres when continuing on a normal diet. These results show that both IgA‐class EmA and AGA are good indicators of jejunal damage in DH. The rapid fall of EmA titres after gluten withdrawal indicates that this test is also useful for monitoring a patient's adherence to a GFD.