Pathologic fractures of the mandible can occur for many reasons including osteoradionecrosis, osteomyelitis, malignancy and cyst. Pathologic fractures are difficult to treat because management is needed not only for the fractures of the mandible but also the underlying disease the is weakening the bone. Additionally, the diseased mandible in the pathologic fracture frequently has abnormal bone healing capacity. We experienced three cases of pathologic fractures of the mandible resulting from cyst, malignancy and osteomyelitis. The treatment of these cases was complicated and time-consuming. Therefore, we present our three cases and discuss the management of pathologic fractures of the mandible.