A leptanalgesia (Chlorpromazine-morphine) was used in the treatment of postero lateral diaphragmatic hernia in six neonates. The treatment which was begun immediately after the arrival of the child and continued during and after surgery seemed to contribute to the favorable outcome observed in five of the babies. In spite of the empirical nature of their argument, the authors suggest the possible mechanism of action of the treatment. However they recognize that its effectiveness can only be assessed after careful hemodynamic studies.