This article proposes an analysis of the commitment of medical people (physicians, apothecaries and surgeons) in the midst of a plague-infested city: involvement both in municipal life, as municipal magistrates or town councillors and in sanitary supervision in times of epidemics. Was the presence of medical people within a municipal council a regular political practice or was it made indispensable by an impending crisis ? They were men of power and were also men on the ground. Some of them took up their pens and wrote down their observations in the shape of notes or short treatises. Such texts, whether they were published or not, reveal their authors' deep-felt personal convictions, fraught with doubts rather than certainties. If the prophylaxes they put forward did not really break new ground, on the other hand, their pragmatic involvement in favour of maintaining urban order show their determinaiton to triumph over the scourge by any possible means, whether they were political means or sanitary measures.