Although more and more luxury goods brands are expanding in the service sector, very little research has yet focused on these strategies of development. Given the risks associated to them, the aims of this article are (1) to define the specificities of product-service extensions and (2) to analyze the internal legitimacy of luxury brands to be launched in the service sector through the analysis of the BEP (Brand Extension Potential). The BEP defines where and how far a brand can be extended according to its emitted discourses and more specifically according to the openness of its brand contracts (delimitation, determination, mastery). A semiotic analysis has been conducted on four luxury goods brands (Armani, Baccarat, Bulgari, Cheval Blanc) that have expanded towards the hospitality sector. It is revealed that the BEP to services depends on the openness of the delimitation and mastery contracts. The results are confronted with the current situations of the brands studied as well as the opinions of luxury consumers. Managerial implications are deduced. Keywords: extension from product to service, Brand Extension Potential, luxury, semiotics.