IDEF0 is a method designed to model the events, data, and activities of an organization or a system. IDEF0 is an IEEE Standard derived from the graphical language: Structured Analysis and Design Technique called SADT. The IDEF0 model helps to organize the analysis of a system and allows promoting good communication between the analysts and the users. It enhances user involvement and allows us to obtain consensus models which is a basic requirement when actors are multidisciplinary such as physicians, nurses, technicians, engineers, administrative staff, managers, etc. The IDEF0 method allows us to model an existing (as-is) or a future (to-be) system, to understand its activities. The structure and abstraction of IDEF0 allow easier understanding of complex systems, and a top-down modular analysis. The analysis of the system (the following figure) is represented as a collection of hierarchically organized diagrams with a limited number of elements: boxes which represent activities and arrows to model physical, information, order flows, etc. IDEF0 will assist us in identifying care units and services, units’ accessibility and the propagations of flows (e.g., staff, patients, relatives). An IDEF0 model will be first created for our hospital analysis and it will be used to identify the critical care units, or the critical technical units, and second to generate a dynamic model in order to evaluate a scenario by calculating the patients’ traffic, or the contaminated patients crossing an infected area, etc.