The subject of the thesis is the free movement of patients in the EU/EEA, in particular the financial coverage in cross-border health care and how it is evolving. Reviewed are both existing and the proposed framework currently under negotiations on EU level, the relevant case law of the Court of Justice and the EFTA Court as well as sources of academic literature. The interest of the EU in social security matters, in particular health care service is examined as well as it is established who has the competence to regulate such matters. Whether reimbursement of cost incurred for cross-border treatment is a Treaty based right of every Union citizen, that is the question. The case-law of the Court is clear on a case-by-case basis, but still there currently is legal uncertainty surrounding the field regarding their general application as the field is evolving and currently under big reform.