SUMMARY An overview of the basic principles, instrumentation, and surgical approaches for internal fixation of mandibular fractures as advocated by the Association for the Study of Internal Fixation has been presented. Most mandibular fractures continue to be treated by conservative means. Those fractures requiring surgical intervention are best treated using internal fixation. Fractures of the edentulous mandible, unstable angle fractures, comminuted fractures with or without avulsion, fracture dislocations of the condyle, and mandibular fractures in the polytrauma patient are some of the relative indications for the use of internal fixation. Application of this technique requires a thorough understanding of the regional surgical anatomy and biomechanics as well as familiarity with the armamentarium and its proper use. Surgical treatment must include the restoration of the preoperative occlusal relation before the fixation of the basal portion of the mandible. Inadequate plate selection and contouring will invariably result in malocclusion, nonunion, and infection. Proper application of internal fixation techniques will lead to primary bony union and, more importantly, to early, pain-free restoration of function in the majority of patients. We have used this method to treat more than 400 mandibular fractures. The overall complication rate seems to be comparable to that with wire osteosynthesis. Most failures can be attributed directly to improper plate selection and contouring. This is an exact system, with little room for error.