Autoimmune thyroiditis has been suggested as a precancerous condition in some adult studies, but there is still controversy. The importance of autoimmune thyroiditis in childhood thyroid cancer is not yet completely clear. We aimed to evaluate in this study the characteristics of childhood thyroid cancer in patients particularly in terms of coexisting factors including autoimmune thyroid disorders (ATD). Twenty patients diagnosed with primary thyroid cancer were evaluated retrospectively in a Pediatric Endocrinology clinic for 10 years. Patients were followed up for 57.22 +/- 11 months. Concomitant conditions (thyroidal and/or extra thyroidal) were determined. Most of the patients (80%) had a coexisting factor. ATDs are the most frequently encountered among them (40%). The ages at the time of diagnosis were older; and the tumor sizes were smaller in patients with concomitant ATDs than without autoimmune thyroid disorders. The follow-up characteristics were similar in both groups. In conclusion, ATDs are frequently encountered in association with thyroid cancer during childhood and adolescence. A thyroid autoimmunity may facilitate the development of a malignant thyroid tumor; on the other hand, increased attention to the thyroid gland may facilitate frequent diagnosis of thyroid cancer. A close follow-up of ATD patients should also include the evaluation of the development of thyroid malignancy.