The occurrence of autoimmune thyroid disorders among patients with coeliac disease (CD) is well documented, but the exact prevalence of CD among patients with autoimmune thyroid diseases (ATD) is as yet unclear. We screened 150 newly diagnosed patients with ATD by serum endomysial antibody detection (EmA). In 5 subjects (3.3%) EmA positivity was found; all underwent jejunal biopsy. On gluten-free diet an excellent clinical and histological response was recorded with an improvement of hypothyroidism and reduction of the thyroxine dosage. Our data suggest a significant high prevalence (3.3%) of CD in patients with ATD, in particular with Hashimoto's thyroiditis.