Mandibular lengthening by distraction osteogenesis is a new method for use in treating congenital deformities or postsurgical bone defects. However, the use of extraoral transcutaneous pins in the mandible has disadvantages, such as facial scars and facial nerve or inferior alveolar nerve injury. The purpose of this study was to establish a new approach to distraction osteogenesis in the mandible by using osseointegrated implants and an intraoral device. Ten adult canines were used for this experiment. After extraction of the teeth and placement of two titanium implants in the left mandible, connection of the intraoral distraction device to the abutments, and corticotomy in the medial portion between implants were performed. Distraction was done at the rate of 1 mm per day to elongate 10 mm in length. Radiographic and histologic examinations showed that successful mandibular lengthening was achieved. New bone was primarily formed by intramembranous ossification and partial endochondral ossification. Titanium implants placed for anchorage of the device remained stable during the course of mandibular lengthening. Study results suggest that the intraoral device using osseointegrated dental implants can be used as a mechanism for distraction osteogenesis in the mandible. Keywords: distraction osteogenesis, intraoral device, mandibular lengthening, osseointegrated implant