A girl approximately 2 years old with Pierre Robin sequence had periods of nocturnal respiratory insufficiency as a consequence of micrognathia and a boy nearly 4 years old with Nager syndrome and tracheostomy was retarded in his speech development, had problems swallowing and often had respiratory tract infections. The obstruction of the upper respiratory tract was resolved by performing a distraction osteogenesis of the lower jaw. A tracheostomy was avoided or else removed. The girl became more active and there was an improvement in the boy's speech development. Distraction osteogenesis is a good alternative to the current practice of mandibular reconstruction in micrognathic patients, which involves extensive bone grafts.