In the European Union, unaccompanied asylum seekers below 18 years of age are entitled to specific treatment. Age assessment practices to verify the age-statement by the asylum seeker differ between EU Member States. Medical methods in use raise questions about accuracy, reliability and safety. The medical, legal and ethical acceptability of invasive methods (notably X-rays) in particular is controversial. Human rights are at stake. The lack of common practices results in different levels of protection (discrimination). The absence of standardisation is an obstacle for the functioning of the Common European Asylum System. EU Best Practice Guidelines should remedy the situation; such guidelines should reflect the best interest of the child.