During 2009, 15,100 unaccompanied children sought asylum in Europe. Many of them came from 'failed states' like Somalia and Afghanistan where official documents with exact birth dates are rarely issued. This has led to requests to health care professionals in many countries to assist migration authorities in determining whether a young asylum seeker is a child or an adult. Many different methods are currently employed in Europe for this purpose by dentists, paediatricians, radiographers and social workers, but no currently available method has been demonstrated to have the accuracy needed to be of real use in this decision. Unclear guidelines and arbitrary practices may lead to alarming shortcomings in the protection of this high-risk group of children and adolescents in Europe. Medical participation, as well as non-participation, in these dubious decisions raises a number of ethical questions. CONCLUSION: To improve care for young asylum seekers with undetermined age, we suggest better legal procedures for the determination of age and a more flexible approach to chronological age.