Objectives : Well differentiated thyroid carcinoma(WDTC) has relatively good prognosis. But recurrence is associated with increased morbidity and mortality, and always results in reoperation. So it is important to evaluate the risk factors relative to the recurrence. The aim of this study is to evaluate the risk factors of recurrence. Materials and Method : Two hundred seventeen patients who had undergone thyroidectomy and proved as WDTC from January 1999 to December 2004 was included in the study. We reviewed patient-related and tumorrelated factors respectively and analyzed the correlation with tumor recurrence. Results : Fourteen patients from two hundreds seventeen had recurred. Recurrence rate was 6.5%, and average interval of recurrence was 28 month. Male, age over 45, multiple mass, and advanced TMN stage patient group show higher recurrence rate, but no statistical significance. However, the recurrence rate of lymph node metastasis, tumor size>1.5cm, and extracapsular invasion group were statistically high. Conclusion : Lymph node metastasis, tumor size and extracapsular invasion are significant risk factors related to the recurrence of WDTC.