Simultaneous occurrence of medullary and papillary thyroid carcinomas in the same gland is very rare. In fact. there are only 18 cases of simultaneous occurrence of medullary and papillary thyroid carcinomas in the literature. We report a case of simultaneous medullary and papillary carcinoma of thyroid gland. A 67-year-old woman was diagnosed with medullary carcinoma of right lobe of thyroid gland and papillary carcinoma of left lobe of thyroid gland by fine needle aspiration cytology. Total thyroidectomy, anterior neck dissection, bilateral modified radical neck dissection and tracheotomy was undertaken. The tumor metastasized to regional lymph node and extrathyroidal muscle invasion of left papillary carcinoma was also revealed by pathological report. This report describes a case of thyroid carcinoma that demonstrated both medullary carcinoma and papillary components in the thyroid with lymph node metastasis.