The article discusses the law applicable to the determination of a property-secured right – i.e. a mortgage. Major reflections are preceded by the legal analysis of a mortgage, the concept of the Eurohypothec and the European Land Information Service – EULIS. What follows is a short review of mortgage regulations in selected legal systems (e.g. the French and German systems). The core of the article focuses on the rules for the search of the law applicable to a mortgage and related scope. The change of law governing mortgages (property), e.g. as a result of the change of borders, including a hostile incorporation (annexation), is also discussed.