Health establishments in France and everywhere else in the world have had to face unprecedented problems during the Covid-19 sanitary crisis. Nevertheless, they managed to cope in a reasonable manner. The question is how could they do it. As bureaucratic organizations working according to pre-established rules and procedures within a hierarchical structure, they are no equipped to tackle sudden serious unexpected problems. This study tries to answer this question. It was led in 4 University Hospital Centres in the French region of Auvergne Rhône-Alpes covering the period from the beginning of the pandemic in January 2020 to the second big wave of contaminations in the Autumn of 2020 divided into 3 Phases (January mid-March 2020, mid-March to mid-May and after mid-May). The theoretical framework for the research was to use the concept of the High Reliability Organization developed by the 'Berkeley School' (1987) and test if hospitals were able to tackle the pandemic by forgetting about their bureaucratic nature and adopting some of the ways of operating of HROs. The findings, through a qualitative methodology, largely prove that the hypothesis was valid. The lessons that can be drawn from this research and that can inspire the authorities managing the health sector are that a new type of organization, known as the flexible bureaucracy (Bigley and Roberts, 2001), could be developed in health establishments to make them ready to face extraordinary events such as a pandemic or other catastrophic similar events. Type of paper: research paper based on case studies.