This article addresses the issue of the autonomy of patients who are not treated in standard situations of hospitalisation in institutions, but who receive ambulatory care. Academic and institutional discourses both suggest that the development of out-of-hospital care delivery models promotes patient autonomy. Through a qualitative study based on semi-structured interviews of cancer patients treated using ambulatory chemotherapy in a French hospital we show that some of the constraints usually encountered by patients receiving care in institutions are also observed in patients receiving ambulatory care. They experience a form of cognitive isolation regarding access to information about their health, and their social life appears to be institutionalised.