Components were isolated from rat liver, sheep lung, rhesus and orang-utan intestine. In enzyme immunoassay, these components detected 57%, 72%, 84% and 88% of human sera containing endomysium and reticulin antibodies (EmA and ARA). At most, 7% of EmA/ARA-negative sera reacted with the antigens. The spectrum of EmA/ARA-positive sera reactive with the various components was different but overlapping. When the antigens of sheep lung and orang-utan intestine were used as a cocktail, 98% of EmA/ARA-positive sera (45/46), but only 2% of control sera (1/46) were detected. The isolated antigens from sheep lung and monkey intestines were able to absorb EmA and ARA from human sera and thus should be suspected to contain the epitopes recognized by EmA and ARA, whereas the rat liver component did not bind. Therefore, the spectrum of autoantibodies in coeliac disease might comprise more than that covered by the terms EmA and ARA. The N-terminal amino acid sequence of some of the antigens was homologous with casein, gliadin, fibrinogen, and collagen.