About twenty percent of the European population are under 18 years of age. There is a great need for documented and safe medicines for neonates, infants and children. Over 10-90% of the medicines used in these age groups have not been tested in these target patient groups, but tested in adults that may have different pattern of metabolism and elimination of the medicines. Management of paediatric trials requires the highest level of ethical standards and scientific rigour. Several diseases in paediatric population are rare and networks of researchers joined together in clinical trials are essential to ensure safe data.