Pan-European collaboration in studies of novel therapies and treatment strategies in childhood cancer is playing an increasing role in the attempt to improve cure rates. Differences in the systems of various countries with regard to drug control and ethical issues may lead to problems and delays. This applies in particular to phase I/II studies in children where the ethical considerations may be complex. In this review, the systems in three large countries-UK, France and Germany-are reviewed and current moves within the European Community towards a more standard approach are discussed.