several studies found a higher prevalence of autoimmune thyroid disease (atd) in patients with chronic urticaria (cu). this relationship may be due to the possible autoimmune etiology in up to one third of the cases of chronic idiopathic urticaria (ciu). however, the frequency of atd ranged from 1.14% to 28.6%. the study began by determining whether there is an association between atd and cu, in a population seen at the same clinic. we compared the frequency of anti-thyroid antibodies and thyroid dysfunction in 49 patients with ciu (group 1) and 112 controls (group 2). in order to support the result found, we studied the prevalence of ciu in 60 patients with atd (group 3) and compared with 29 patients who had non-immune thyroid disease (nitd) (group 4). we did not find a statistical difference for the presence of anti-thyroid antibodies or thyroid dysfunction between groups 1 and 2 (12.24% x 9.82% and 12.24% x 7.14%, respectively). the same occurred for the presence of ciu among groups 3 and 4 (3.33% x 3.44%). in our study it was not possible to demonstrate a relationship between atd and ciu, which means that different populations may present a higher or lower degree of association between these illnesses.