The ultra structural binding sites of endomysium antibodies have been studied on human umbilical cord tissue. The sensitivity and specificity of IgA endomysium antibodies were compared with recently described methods using basement membrane of smooth muscle of monkey oesophagus. Thirty adults affected by coeliac disease (10 in remission) and 75 healthy adult controls with normal intestinal mucosa (35 false antigliadin positive) were investigated. Sensitivity and correlation of endomysium antibodies with total villous atrophy in untreated coeliac disease patients were 100% on the human umbilical cord smooth muscles, and only 90% on the muscular layer of primate oesophagus. Indirect immunofluorescence was superior to peroxidase staining in detecting these IgA antibodies. The easy availability and enhanced testing sensitivity of the umbilical cord is an advance towards a better diagnostic tool for coeliac disease.