A total of 203 patients with insulin-dependent diabetes mellitus (IDDM) were screened for coeliac disease (CD) by means of serum IgA and IgG antigliadin (AGA) (ELISA) and total anti reticulin antibody (ARA) IFL assay. As suggested by Savilhati, the combination of the IgA and IgG AGA test with IgA titration in serum (to find IgA deficient individuals) identifies almost 100% of CD patients. In this study ARA antibody assay was performed and two new suspect coeliac cases were found among IgA AGA negative children. Together the ARA and AGA tests give a 3% overall prevalence of CD in IDDM. The confirmation of CD must still be obtained with jejunal biopsy. Even high titres of AGA IgG are less specific for coeliac disease and in IDDM may identify those patients who are immunologically more hyperreactive.