Using unpublished archival sources, this essay analyses the development of convent pharmacies in sixteenth-century Florence and situates them in a changing medical and political landscape. These female-run apothecary shops shed light on several important issues for historians of Renaissance medicine and society: the nature and extent of women's medical agency; the acquisition and transmission of specialized knowledge outside a university or guild setting; the regulation of unofficial practitioners by guild and state authorities. By producing and marketing drugs to the public, Renaissance religious women both augmented the medical resources available in Italian urban society and acquired roles of public significance beyond the spiritual realm. I analyse the roots of convent pharmacies in new social welfare initiatives circa 1500, then consider their products, clientele, business practices and methods of training new practitioners. Finally, I ask how convent pharmacies were regulated and why they were protected by early Medici dukes. I argue that Florentine convent pharmacies remained vigorous entities throughout the sixteenth century despite tighter enclosure provisions and professionalizing aspirations, partly because contestations over their status enabled Cosimo I de' Medici and his successors to advance their personal authority within a centralizing state.