PURPOSE: Thyroid cancer is a rare disease in pediatric population, but its incidence rate is increasing. The aim of this report is to present a single institution experience of pediatric thyroid cancer and to identify clinical features, predisposing factors, and postoperative course of pediatric thyroid cancer. METHODS: We retrospectively reviewed 35 pediatric patients who underwent operation due to thyroid cancer at Seoul National University Children's Hospital between May 1997 and January 2017. The median follow-up period was 70 months (range, 5–238 months). RESULTS: The mean age at operation was 12.0±5.91 years and 27 patients were female. The underlying conditions in patients included history of chemoradiotherapy for previous other malignancies (n=4), hypothyroidism (n=3), history of chemotherapy (n=2), family history of thyroid cancer (n=1) and history of radiation therapy (n=1). The initial symptoms were palpable neck mass (n=21) and incidental findings (n=11). Total thyroidectomy (n=30) or unilateral lobectomy (n=5) were performed. There were 15 postoperative complications including transient hypocalcemia in 14 patients and Horner's syndrome in 1 patient. The most common pathologic cell type was papillary thyroid cancer (n=29). Extrathyroid extension and lymph node invasion were found in 25 patients and 27 patients, respectively. Thirteen patients showed multifocality. During follow-up period, 5 patients underwent additional operation because of tumor recurrence in lymph nodes. Lung metastasis was detected in 3 patients at the time of diagnosis and in 3 patients during follow-up period. The mortality rate was zero and mean disease-free survival was 83.7±47.9 months. CONCLUSION: Pediatric thyroid cancer has lower mortality rate and recurrence rate as seen in this study despite the advanced stage at diagnosis. A thorough follow-up of patients with an underlying condition such as history of chemoradiotherapy and understanding new pediatric guideline can be helpful to maximize patients' survival and prognosis.