Positional plagiocephaly in the newborn corresponds to a posterior flattening and asymetry of the head. Its incidence has significantly increased since the "back to sleep" campain in the nineteen nineties to prevent sudden infant death syndrome. The posterior deformation usually worsens during the first six months of life when the skull is susceptible to posterior constant pressure which induces the deformation. Spontaneous outcome can be favorable. Treatment is always conservative and consists in positionnal exercise, physiotherapy and osteopathy. In some cases treatment with a helmet is recommended for a period of three months usually. Posterior positionnal plagiocephaly has no consequences on the brain's developement an is considered as an esthetic issue. In most cases good results are obtained after management with a custom fitted helmet when needed.