Distraction osteogenesis is a bone creating procedure that can contribute materially to the treatment of Class II dento-skeletal disorders where the mandible is under-sized. Still, the serious commitments this treatment demands and the unpredictability of its occlusal results oblige practitioners to pinpoint precisely the indications for its use. We now believe that distraction osteogenesis can beneficially be employed for: 1--Adults with Class II malocclusions, a small mandible, and a lack of harmony between tooth and jaw size. This bone growing technique makes it possible to treat these patients without the extraction of premolars that would have been necessary in the traditional preparation for orthognathic surgery. 2--Patients whose mandibles are diminished in size in the area of the symphasis. Distraction osteogenesis of this anterior segment is the only way they can be treated without reduction of tooth structure or excessive labial tipping of teeth. 3--Some patients with short, or moderately short rami. We do not, at this time, believe that distraction osteogenesis is indicated for the treatment of any other kind of dento-facial deformity. But, in the future, improvement of surgical techniques and the miniaturization of appliances will doubtless extend its scope.