Based on serial antibody analysis [gliadin (GA) and endomysium (EMA)], the prevalence of coeliac disease (CD) was 6/1970 (0.30%). In autoimmune chronic hepatitis 5.4% and in IDDM 2.6% had CD, why screening for CD could be motivated. IgA-GA positivity was increased in alcoholic liver disease, PBC, primary sclerosing cholangitis, chronic hepatitis, hepatitis C, IDDM, NIDDM, and in secondary diabetes to 11-24% compared with blood donors (5%). CD was correlated with HLA-DQ2/DR3, while DQ1, DQ7, DR1, DR4 and DR5 were inversely correlated. 79% of GA-positive but healthy individuals had DQ1, which would be expected to confer protection. The findings suggest GA- positivity to be independent of the HLA genotype in CD. From 848 IDDM patients 16 high titre GA patients were selected. Chronic thyroiditis, thyroid peroxidase, factor XIII IgA antibody positivity and HLA DRB1*13 were correlated with GA-positivity, while tissue transglutaminase IgG titres were inversely correlated. A patient with CD and antibodies against the active site of factor XIII is described. In 20 patients with EMA no correlation between tTg and factor XIII was observed.