Childhood cancer is a relatively rare disease, representing just 1% of all malignancies. Within Europe, this represents some 12,000 new cases each year, with approximately 1600 a year in the United Kingdom and 1800 in France. International collaboration in phase III trials of childhood cancer has been the norm for many years, traditionally within Europe, but, largely because of organisational considerations, phase I and II trials have only been conducted on a national basis. With overall cure rates in the region of 70%, relatively few children are available for these early drug trials. Access to new drugs is also a major problem. Against this background, a United Kingdom (UK)/French 'new agent' collaboration was established, expanding subsequently into a wider European grouping. This paper documents the history of that collaboration, the outcomes and future challenges.