Chondrosarcoma of the skull base is a rare slow-growing tumor with a potentially lethal outcome due to compression of adjacent tissues. Total surgical excision is often difficult due to local anatomical limitations. The differential diagnosis among chondrosarcoma, chordoma, and chondroid chordoma is important due to their different prognoses. We describe two cases of chondrosarcoma with initial presentations of diplopia. Magnetic resonance imaging (MRI) in each case revealed a skull base tumor. After tumor excision, histopathologic examination showed a grade Ⅰ chondrosarcoma. In conclusion, accurate diagnosis and careful surgical treatment play important roles in the management of chondrosarcoma.