Controversies remain regarding to the therapeutic methods of papillary thyroid cancer (PTC) in young patients. TNM staging and other risk evaluation system are not perfectly applicable for all young PTC patients in view of disease outcome. The aims of this study are to identify the clinical presentations, prognostic factors and risk analysis methods. From January, 1977, to June, 2006, seventy-seven patients with primary PTC younger than 20 years old at Chang Gung Medical Center in Taiwan were enrolled in this retrospective study. The patients were classified as disease-free or non-disease-free according to presence or absence of distant metastases or local recurrence at the end of follow-up. Clinical data of these patients were analyzed and compared. The average follow-up period was 10.3 years. Two patients died of PTC during the follow-up period; one died of brain metastasis, and one died of airway obstruction. Patients undergoing total thyroidectomy, especially those with disease beyond the thyroid, had better outcomes than patients not undergoing total thyroidectomy (p = 0.003). Moreover, the DeGroot clinical classification system was a better predictor of prognosis than TNM (p<0.001 vs p = 0.007). Our results suggest that prognosis for PTC is not worse in younger patients. However, patients who had undergone total thyroidectomy might have a better prognosis. Clinical classification is a good alternative classification system for predicting disease outcome in young PTC patients. Patients with confined intrathyroid lesion (≤T2, N0, M0) may be regarded "low risk" PTC patients.