A retrospective, controlled study was undertaken to determine the prevalence of autoimmune thyroid disease in 111 adult patients with allergic (77) and nonallergic (34) rhinitis seen in a private ENT/allergy practice in the lower Hudson Valley, New York. The control group consisted of 101 patients with no history of chronic rhinitis. Autoimmune thyroid disease was found in 10.4% of the allergic rhinitis group, 14.7% of the nonallergic rhinitis group, and 9.9% of controls, with a trend toward higher prevalence in the nonallergic rhinitis group compared with controls. No statistically significant association was noted between the 3 groups. The female-to-male ratio in the nonallergic rhinitis group was approximately twice as high as in the control group.