An association between celiac disease and other autoimmune disorders--such as insulin-dependent diabetes, Addison's disease, systemic lupus erythematous, rheumatoid arthritis, alopecia areata, and autoimmune endocrine diseases--has been described. The aim of this study was to evaluate the prevalence of celiac disease in 100 patients with autoimmune thyroid disease. Moreover, the monitoring of patients with concomitant celiac and autoimmune thyroid diseases, after a gluten-free diet or a gluten-containing diet, can give important insights into the effect of dietary habits in thyroid autoantibodies modulation. In our study, the prevalence of celiac disease in patients with autoimmune thyroid disease was 2%. In these two celiac patients, the serologic markers became undetectable 6 months after beginning a gluten-free diet. However, thyroid autoantibodies did not positively correlate with dietary habits.