The most appropriate time and way to inform parents of a diagnosis of mongolism is often discussed among physicians and others who have early contact with mongol children. Despite this, however, few attempts have been made to ascertain systematically the views of the parents themselves. We have had an opportunity to do this in the course of a clinical and cytogenetic investigation of mongolism. Information on the subject was obtained from 95 mothers of mongols, all of whom were personally interviewed by at least one of us during the past three years. Nearly all the parents were from north-west London and adjoining counties, and represented all social classes.