BACKGROUND: Previous studies yielded conflicting results regarding the presence of an association between coeliac disease (CD) and psychiatric disorders including depression. This association has not been studied in the United States. AIM: To determine the prevalence of psychiatric and autoimmune disorders in patients with CD in the US compared with control groups. METHODS: In a case control study, the prevalence of psychiatric and autoimmune disorders was compared in 600 CD patients, 200 irritable bowel syndrome (IBS) patients and 200 healthy controls. RESULTS: The prevalence of depression in CD was 17.2% and was similar to that in IBS (18.5%, P = 0.74) and controls (16.0%, P = 0.79). Among CD patients, type I diabetes mellitus (DM) was identified as a significant risk factor for depression (P < 0.01) with 37% of patients with both CD and type I DM having clinical depression. CONCLUSION: The prevalence of depression in CD is similar to that in other chronic gastrointestinal diseases and healthy controls. However, there is a markedly elevated risk of depression in patients with both type I DM and CD. Differing rates of type 1 DM among coeliac populations may account for disparity in published rates of depression in patients with CD.