OBJECTIVE: Coeliac disease (CD) is associated with autoimmune thyroid disease. Gluten sensitivity represents a spectrum, with at one end cases with severe gluten-dependent enteropathy, and at the other subjects with minor signs of deranged mucosal immune response. The aim of this paper was to look for signs of minor small bowel injury and immunohistochemical markers of gluten sensitivity in a group of patients with Hashimoto's disease. SUBJECTS AND METHODS: Fourteen patients with Hashimoto's thyroiditis without serological evidence of CD underwent immunohistochemical analysis of jejunal biopsies. RESULTS: In 6/14 cases (43%) an increased density of gammadelta T cell receptor bearing intra-epithelial lymphocytes was found. In 6/14 (43%) signs of mucosal T cell activation (presence of interleukin 2 (IL2) receptor (CD25) on lamina propria T cells and/or expression of human lymphocyte antigen (HLA)-DR molecules on crypt epithelial cells) were noted. In 4 out of 6 such cases, HLA haplotypes were described in association with CD. CONCLUSION: A significant proportion of patients with Hashimoto's thyroiditis present signs of 'potential' CD and of activated mucosal T cell immunity. The gluten dependence of such findings remains to be ascertained.