Louis Odier was an active physician in late Eighteenth century Geneva. Studying his medical practice conveys an idea of the social impact of a doctor on the local medical market at the time. He encountered a series of economic and professional difficulties for which he found original solutions. Convinced that the practicing physician was capable of offering the best services, he sought to defend professional interests. By his intellectual and public activities, he contributed to medical knowledge and to medical policies; in his practice and by his reflexive thought, he drew the contours of an « ethical » professional figure.