Clinical trials have a fundamental role in promoting an evidence based use of drugs in adults and in children. However, it is often difficult to identify the few paediatric studies carried out and to thus implement knowledge derived from them. Furthermore, studies that are stopped prematurely or that have insignificant or negative results often remain unpublished, leading to duplication of effort by researchers, waste of resources and concealment of potentially toxic risks. The European Community decided to support the development of a European register of clinical trials in children as part of the Fifth Framework Thematic Programme "Quality of Life" in 2002. The project DEC-net is coordinated by the Laboratory of Mother and Child Health of the Mario Negri Institute for Pharmaceutical Research in Milan and currently involves members of four countries; France, Italy, Spain and the United Kingdom. It is unique in that it is the first population oriented clinical trial register. Such a register represents a useful source for planning new studies, promoting communications and collaborations between researchers, facilitating patient access and recruitment into trials, preventing trial duplication and inappropriate funding and identifying the therapeutic needs of children that remain neglected. It will also allow for active monitoring of new or evolved knowledge of drug therapies.