Borders delimitate political-administrative systems that adopt different sets of rules and procedures dealing with different matters. Regarding cross-border health care, our analysis shows that in some contexts, as is the case in a semi-federal state as Spain, problems and solutions can be applied to external borders (between states) and also to internal borders (between autonomous regions). First, we treat cooperation at the external ones. Once described European and Spanish legal frameworks, a case study is analysed, that of Cerdanya (Spain-France border). Then, we turn our attention to horizontal cooperation between Spanish regions, the National Health System and the funds to balance spending between regional administrations. Two cases studies (Catalonia-Aragon and La Rioja-Euskadi) will show the tensions and negotiations between regional governments, which have driven to search a solution within the state framework.