This study concerns a retrospective analysis of 85 case histories of pre-natal dilatations of the ventricles considered by a multi-disciplinary group whose aim it was to try and identify the most favourable features for prognosis that could be found in the whole of this pathological condition. The prognosis for ventricular dilatations found in utero is very poor. Only 36 of the 85 children were born alive. 16 of those died before they were two months old and of the survivors only 4 children developed normally. The least unfavourable elements that were found seem to be solitary areas of dilatation or the association of the dilatation with agenesis of the corpus callosum, late diagnosis, slow evolution and a ventricular-hemisphere ratio no more than 50% of the normal value. Early diagnosis should improve the methods of treating these patients. In order to achieve this, an ultrasound of the skull should be carried out in the fourth month and in the 26th week of pregnancy. Precise diagnosis must be made. A attempt should be made to work out the aetiology as completely as possible as well as to watch carefully how the condition is evolving. When death has occurred, the assessment should be compared with the autopsy results. Finally, the knowledge about the outcome of all these children should make it possible to criticize the decisions that have been taken for management.