`titrebOrganizational risks prevention in ambulatory: A comparative study of 4 ambulatory clinics`/titreb“Hospitalizations must be less frequent and shorter. That’s why I want to double the number of ambulatory surgeries.” Says Marisol Touraine, Minister of Social affairs, Health and Woman Rights. Her objective for 2016 is that half of surgeries should be realized in an ambulatory service. The ambulatory surgery tends to become the norm. But it is a real cultural change and a complex organizational process which impose to think differently the access of healthcare and its treatment. In this perspective, some studies made by the ANAP (National Agency of Support for the performance of hospitals) and the HAS (High Authority of Health) were published in 2013. These studies help the professionals to develop their ambulatory practices by using the approach “LEAN” as a global organizational system. What is the use for the professionals? What are their perceptions of this Lean Management? And how do they protect themselves from the organizational risks of this Management? A comparative study of 4 ambulatory services showed the main risks for the professionals (put in tension and stiffening of the work) as well as the technical, organizational and human means they must have. It appears that the private hospitals (where the studies were done) managed to face the flux and protect the organizational slack necessary for the cohabitation of an organizational standard and unique relation.