We encountered a rare case of a calcifying epithelial odontogenic tumor with cyst formation. The patient was a 28-year-old man with swelling in the anterior mandibular region. Panoramic and intraoral imaging showed a clear, unilocular, radiolucent lesion with bony boundaries. Many small radiopacities were apparent in the radiolucent area. Clinically, the lesion was thought to represent an odontogenic tumor involving calcified bodies. Multidetector row computed tomography showed small radiopaque bodies arranged in a regular circular manner on the outer rim of the radiolucent region, which showed an attenuation value of approximately +20 Hounsfield units. This appearance strongly suggested a calcifying cystic odontogenic tumor, and the final diagnosis was a calcifying epithelial odontogenic tumor with cyst formation. According to the 2005 World Health Organization Classification of Tumours, cystic changes are not seen macroscopically in calcifying epithelial odontogenic tumors. We thus consider this to be a very rare and interesting case.