This article explores the implementation of professional medicine in Chile in the second half of the 19th century. It focuses on lawsuits filed by certified physicians against men and women who did not have the official medical qualifications required by law to practice medicine. Based on these records, this study investigates the efforts made by professionals to legitimize the knowledge, ideals, and roles that seemed to define their identity. At the same time, the study reviews the notion of professionalization instilled by historiography as a successive and orderly process of the acquisition of credentials that led to the formation of two types of space, one expert and the other amateur.