A case of a very rare combination of diffuse sclerosing variant of papillary thyroid carcinoma (DSPC) and primary squamous thyroid carcinoma (PSC) is presented. A 25-yr-old woman with right-sided neck mass and hypothyroidism was admitted. US showed that the right lobe of the thyroid gland was enlarged with irregular margins and heterogen echogenity and there were multiple small punctate echogenic foci in the central portion. A scintigraphy with 99mTc showed decreased uptake in the right lobe. FNA of the right lobe induced us to consider the presence of follicular neoplasm. Chest roentgenogram was normal. Total thyroidectomy with right-sided modified radical neck dissection was performed. Findings related to Hashimoto's thyroiditis and abundant psammoma bodies were observed in the frozen sections. Histopathologic findings demonstrated the coexistence of DSPC and PSC in both lobes and 16 lymph nodes metastases and soft tissue infiltration. Radioiodine was administered to ablate residual thyroid tissue. She was given T4 suppression therapy. At the 44th month of follow-up, she remains well without recurrences and metastases. The coexistence of DSPC and thyroiditis or PSC is still under debate. Very few cases with the combination of papillary thyroid carcinoma and PSC have been reported previously, thus we discuss the clinico-pathologic features and possible explanation for this unusual coexistence of malignancies.