Our understanding of medical practice in early modern England has for some time been shaped by the poorly-characterised concept of the ‘medical marketplace’. But what was the ‘medical marketplace’? How far did it extend beyond the urbanity of London? Who traded within it? And what was being bought and sold? The British Library is home to three collections of rare medical advertisements dating from around 1660 to 1720, most of which take the form of handbills; these unique sources allow us to sketch a fresh picture of the ‘medical marketplace’ of this period, including the rise of the patent medicines that would become increasingly prominent over the course of the eighteenth century. They also allow us to consider how the practitioners and vendors of medical goods that traded within that marketplace, from university trained physicians to producers of single nostrums, presented themselves to potential customers, and give insights into how the medical market was structured, and what issues were contested by its participants. Integral to trade within any market is the credibility of the vendor, or in this case, the practitioner or dispenser. This paper will investigate some of the ways in which practitioners and nostrum-peddlers made use of the burgeoning medium of cheap print to cement their authority and bolster their reputations as legitimate practitioners in the reading eyes of their potential customers. This struggle to secure a popular reputation, and thus, a toehold in a highly competitive (and profitable) market, is framed against the background of contemporary struggles between the College of Physicians, the Society of Apothecaries and other institutions to assert their right to regulate medical practice and the sale of drugs in this brief