Historical and sociological studies have often examined patient-doctor relationships in terms of power. If today medical power is being called into question, because of legalisation of patient-practitioner relationships and because of the weight of patient associations, a lot of studies have shown that with the arrival of clinical medicine and the medicalisation of hospitals, medical discourse has imposed its power and reduced the free will of patients. This intervention proposes to examine the medieval situation and, in particular, the development of what could be interpreted as a kind of personalised medicine. It is part of a collaborative project aimed at producing a book about these relationships, studied from the Middle Ages to the beginning of the 20th century. With the progressive development of a doctrine and efforts to regulate medical practice, special texts were produced from the 13th century onwards: the writing of therapeutic consilia and regimina sanitatis has resulted in an impressive number of texts, distributed by a large number of manuscripts and editions. Often written by the medical ‘elite’ for specific people, these texts propose a kind of personalised medicine, mediated by writing, that also corresponds to particular forms of relationships, which could be described as negotiated or even, in a way, contractualised.