PURPOSE OF REVIEW: To update information about pediatric thyroid cancer. RECENT FINDINGS: This review of thyroid nodules in children indicates that the incidence of thyroid cancer has been steadily increasing over the last 30 years. Knowledge of factors which predispose to the development of thyroid cancer - radiation exposure and family history of thyroid cancer or personal or family history of familial syndromes associated with thyroid cancer - can help determine the aggressiveness with which the diagnostic studies of thyroid nodules should be pursued. Presence of thyroid nodules should prompt measurement of circulating thyroid-stimulating hormone. Thyroid nodules should generally be studied with thyroid ultrasonography; those greater than 0.5-1 cm in diameter which are not simple cysts should be studied with fine-needle aspiration (FNA). When cytologic analysis is indeterminate, a number of molecular techniques may assist in determining which patients should undergo thyroid surgery. SUMMARY: The relative frequency of indeterminate cytology on FNA could necessitate surgery in a large number of patients who will be found to have benign lesions. A number of molecular techniques are available to identify patients with indeterminate cytology who can confidently be followed without surgery as the probability of malignancy is low.