We recently encountered an interesting tumour, containing both a diffuse sclerotic border and calcified bodies, which was eventually diagnosed as a central odontogenic fibroma. The patient was a 40-year-old man with a painless radiolucent area in the crown area of the unerupted left lower third molar shown by panoramic radiography. Clinically, the lesion was thought to represent an odontogenic tumour involving a calcified body, i.e. calcifying cystic odontogenic tumour, calcifying epithelial odontogenic tumour or ossifying fibroma. Diagnosis by radiographic findings was extremely difficult.