This paper presents new research from an ongoing project that explores the nature and extent of eighteenth-century enslaved Africans’ access to smallpox inoculation — and that also considers how this access or lack thereof at once impacted slavery and reflected Atlantic world debates about the safety and efficacy of inoculation. Despite the scarcity of direct historical evidence that inoculation was practiced in more than a few regions of sub-Saharan Africa, many historians posit widespread knowledge and implementation of the technique among enslaved Africans imported into mainland North America. In contrast, other historians cite trading company and garrison records to argue not only that inoculation was uncommon in the sub-Saharan African regions from which most Africans enslaved in North America hailed, but also that unchecked smallpox, aided by mistrust of inoculation among European and North American ‘traders’ and ‘owners’, was one of the hallmarks of Atlantic slavery’s depiction in print advertisements. Examining a Philadelphia case study’s relationship to British-controlled Africa and the British West Indies, this paper explores the historical debates surrounding African American inoculation via the slave sale and runaway advertisements that appeared regularly in the Pennsylvania Gazette, eighteenth-century North America’s foremost periodical. Drawing upon a survey of over 2,000 advertisements that appeared in the newspaper from 1730 to 1800, I juxtapose the adverts’ descriptions of enslaved bodies with municipal statistics, trade and auction records, medical treatises, hospital records, and the practice diaries of several local physicians, including Benjamin Rush. I argue that the advertisements illustrate that: (1) smallpox scars reinforced the institution of slavery by facilitating both slave sales and the apprehension of runaways; (2) scars that historians have attributed to “natural” smallpox might in fact reflect inoculated smallpox; (3) moderate smallpox scarring and the notation “has had the smallpox” were used to connote both inoculation and “natural” smallpox; and (4) Philadelphia-area slave ‘owners’ and ‘traders’ shared the doubts about inoculation’s safety, efficacy, and suitability for the enslaved that gripped other portions of the Atlantic world. For these reasons, I argue, slave sale and runaway advertisements embody inoculation’s contested status in the eighteenth-century Black Atlantic.