PURPOSE This paper aims to attempt to explore current transformations in hospital governance by tracing the evolution of medical autonomy in the Belgian hospital sector in the second half of the twentieth century. DESIGN/METHODOLOGY/APPROACH Using published secondary sources and archive data the paper developed a historical approach to the relationship between profession and organisation, asking qualitative questions of the characteristics of professional power and knowledge. FINDINGS Since World War II, two important evolutions have occurred: first, the hospital evolved into an organisational entity that is described as a "professional bureaucracy"; second, at the sectoral level the hospital adopted a position that is characterised as a "divisional structure". Both evolutions are linked by the processes of rationalisation and bureaucratisation. The findings do not support the thesis of an overall loss of autonomy but bring into focus the transformation of medical autonomy. New forms of professional power and knowledge are emerging with the processing (bureaucracy) and pre-processing (rationalisation) of information on medical work as key elements. ORIGINALITY/VALUE The paper explores the evolution of the medical profession's autonomy in the second half of the twentieth century. It highlights reflexivity in the changing relationship between professions and organisations and how physicians are becoming "managers of expertise" who are important for both the hospital organisation and the state.