Uni- or bilateral mandibular hypoplasia can be associated with various syndromes or is acquired after early traumatic or inflammatory disease in the temporomandibular joint (TMJ). Early treatment is necessary to avoid consequent impairment of midfacial growth. The standard treatment of these malformations consists of the application of bone grafts which can lead to unpredictable growth. Furthermore, these procedures often require intermaxillary fixation and sometimes blood transfusions. Lengthening of the mandible by gradual distraction, according to the method of Ilizarov, opens new perspectives for interceptive therapy. This paper reports on this method applied in 9 cases of mandibular hypoplasia. Out of 3 bilateral and 6 unilateral mandibular distractions the average amount of bone lengthening was 21 mm, ranging from 15 to 25 mm. In order to facilitate ossification, the mandibles were maintained in external fixation for an average of 9 weeks subsequent to the period of active lengthening. Thereafter, immediate postoperative orthodontic treatment is necessary to avoid a relapse. No complications were noted during the follow-up period (max 17 months).