Hospital services have continued to grow year by year due to the aging of the population and the development of chronic and emerging diseases. The pressure of the number of patients, the limited resources available and the multiplication of unexpected situations make it difficult to manage these services on a daily basis. In addition, the budget environment requires healthcare facilities to better control their costs (flat rate pricing for the activity) through better organization of flows and pooling of available resources / services. The objective of the thesis is to implement optimization tools and decision support for the organization and management of flows (materials and patients) in a hospital or a hospital group (GHT). The issue concerns the difficulty of reorganizing and optimizing the different flows of a hospital or a GHT by considering the three levels of planning: strategic, tactical and operational. This reorganization is all the more complex as the human and material resources are limited and evolving. Taking into account uncertain, real-time and dynamic aspects increases the complexity of the problem.