The association between chronic idiopathic urticaria (CIU) and thyroid autoimmunity has most often been suggested in studies investigating thyroid microsomal antibodies, which are less sensitive and specific than anti-thyroperoxidase antibodies, moreover these studies were not case-control studies in large series. By comparing a large patient series presenting with CIU with a large numbered control group we aimed to learn the extent of autoimmune thyroid disease. We compared the frequency of thyroid autoantibodies in 140 patients with CIU with 181 age-and sex-matched volunteers. Thyroid function tests and thyroid autoantibodies were measured by chemiluminescent immunometric assay in study groups. The frequency of thyroid autoantibodies was significantly higher in patients with CIU than that in healthy controls (29.28 %/5.52%; p < 0.001). Of 41 patients, 10 had thyroid dysfunction and the other cases were euthyroid. The higher frequency of these antibodies in our patients shows that there was a strong association between CIU and thyroid autoimmunity.