Biopsy is onerous and, for this reason, immunodiagnostics in sera of celiac disease patients are an "additional diagnostic standard." The objective of the study was to investigate the variability in diagnostic specificity of ELISAs for the detection of IgA anti-tissue transglutaminase antibodies in serum of celiac disease patients who underwent biopsy. All patients were included in the study on the basis that they had a small intestinal biopsy. We studied 18 patients with histological proven celiac disease (7 male, 11 female, mean age +/- SD: 35+/-19 years) from Graz, Austria. Healthy control subjects were also entered into the study. The determinations of the anti-tissue transglutaminase antibodies were simultaneously performed together with the endomysium and gliadin antibody markers. We analysed the 216 serum values according to Cochran's non-parametric Q-test. The complexity to the analysis reflects the complexity of the diagnostic situation with the patients. No real differences were found in the reactions of the anti-human IgA-type anti-tissue transglutaminase ELISAs. Based on these results, an association was established between the outcomes of anti-human IgA-type ELISAs for the specific antigen and patients with histologically proven celiac disease, treated for celiac disease after histology was carried out and the diagnosis was made, and healthy controls. The detection of IgA anti-tissue transglutaminase antibodies in serum is a promising alternative to the indirect immunofluorescence determination of IgA-type endomysium antibodies. One ELISA for the specific antigen showed some advantage with respect to its extended scale of detection. Immunopathology of celiac disease can be based on the results of the appropriate IgA anti-tissue transglutaminase ELISAs under uncomplicated gastrointestinal conditions.