In an increasingly multicultural Europe, Greece and more intensively Great Britain are faced with the need for protection of religious freedom of individuals or social groups. The question becomes more precise but also acute if it is approached with regard to the right to manifest own religious beliefs in the frame of RE as primary instrument of educational policy, but also in the frame of collective worship. This study is focused on the legislation and the administrative practice concerning primary and secondary schools. It covers both the national and international law provisions permeating the Greek and the British legal order. Leading case law of the Greek Council of State has recently confirmed the obligatory character of attending RE at primary and secondary schools. However, protection is also guaranteed by case law to the parental right to declare in writing before the school authorities that due to conscientious reasons a pupil should be exempted from the duty to attend RE and/or collective worship. Notwithstanding the above a survey of school practice today has shown that only a very limited percentage of parents or guardians have made use of this right. Individual application according to art. 25 ECHR offers additional legal security to Greek citizens in case of a human right infringement. In Britain the ERA 1988 provides for the protection of religious freedom concerning RE, while granting the parents the right of withdrawal of their children from RE and collective worship. Beyond any questions of legislative background it remains always a matter of government policy to support effective protection of the right to RE in favour of minorities. ECHR and case law concerning art. 2 of the First Protocol offer a safe legal basis for ultimate correction of possible unfair judicial handling on national level concerning the right to religious freedom.