The Dutch Paediatric Surveillance System was initiated by the Dutch Paediatric Society and is housed within the TNO Prevention and Health office. The purpose of the surveillance system is (a) to gain insight on a population level into the prevalence of rare and new diseases in youths (0-18 year), and (b) to promote scientific research addressing the background, nature and prognosis, as well as the treatment and prevention, of these diseases. A monthly report card is sent to all clinically active paediatricians with maximally 10 diseases under surveillance. The response rate is approximately 90%. The information from the registration can lead to primary or secondary prevention (prevention of the disease or of its complications, respectively). The system provides information for the amelioration of quality of care and for health management and, at the same time, acts as an instrument for scientific research.