OBJECTIVE: Augmentation genioplasty corrects vertical chin deficiency. To stabilize the synthesis and to allow ossification, a biomaterial prop is necessary. Third molars are frequently removed during orthognathic surgery and provides good material used as autogenous grafts. METHODS: This article describes the surgical technique of an augmentation genioplasty using a third molar as a prop biomaterial. Results are stable in time. This technique presents no risk of infection and is less invasive than other autogenous bone graft. CONCLUSIONS: third molar can be used as a prop biomaterial in augmentation genioplasty.