Abstract: Objective To report the prognosis of a patient with simultaneous medullary and papillary thyroid cancer after 5 years follow-up and discuss the pathogenesis, diagnosis, management and prognosis of this disease. Methods The patient with simultaneous medullary and papillary thyroid cancer was a 52-year-old female who had undergone thyroidectomy in a provincial third-grade class-A hospital in July 2011. The surgery was performed by an experienced surgeon and the surgical procedure was right lobe of thyroid and isthmus resection +left lobe of thyroid subtotal resection +central lymph node dissection. Postoperative routine pathologic diagnosis was medullary thyroid carcinoma with d=0.5cm and papillary carcinoma with d< 0.1 cm on the right lobe of the thyroid. Cancer metastasis lymph node was not found in central region of neck (0/5). After 5 years of follow-up, the prognosis was evaluated and discussion was made based on its related literature review. Results Postoperative TSH was controlled within the range of 0.006 -0.289 μIU/ml, and serum calcitonin within 0.52-0.79 pmol/L. Latest reexamination showed that serum procalcitonin was 0.68 pmol/L, CEA of 2.9 μg/L, TSH of 0.256 μIU/ml, FT3 of 4.91 pmol/L, and FT4 of 22.79 pmol/L. The result of endocrine suppression therapy was satisfying and the neck ultrasound results were normal. No recurrence and metastasis was found in 5-year follow-up. Conclusion Surgery is considered as the best treatment on simultaneous medullary and papillary thyroid cancer. This kind of case is rare, and the prognosis is good in this case.