The enterprise strategy is influenced by the environment changes: socio economic, legislative, technology, and the globalization. This makes its Information System more complex and competition increasingly fierce. In order for an enterprise to ensure its place in this hard context characterized by rapid and random changes of the internal and external environments, it must have fast adapting policy of its strategy and drive quickly important changes at all levels of its Information System in order to align it to its strategy and vice versa; that‟s, it must always be agile. Therefore, agility of the Enterprise Information System can be considered as a primary objective of an enterprise. This paper deals with agility assessment in the context of POIRE project. It proposes a fuzzy logic based assessment approach in order to measure, regulate and preserve continuously the Information System agility. It also proposes a prototype implementation and an application of the proposed approach to a tour operator enterprise.