Created at the end of the Hundred Years War, the county of Dunois, entrusted to Jean d'Orléans, and its capital Châteaudun, has an activity related to leather work documented by a hundred registers of the tabellionage. Located on the margins of the Chartrain and Orleans this princely seigneury has not been the subject of an in-depth study since the work of Geneviève Duc on the economy of Châteaudun during the Franco-English conflict. Recent archaeological research and some synthesis work complete our information. However, far from the major political and economic centres of the region, such as Orléans and Tours, but also Chartres, or Blois, a lucrative activity is developing that puts the many tanners at the forefront of the county’s economic life. The notarial records allow to understand the work of these craftsmen through the techniques used (the installations, the products used for tanning), the workshops of production and life allowing to bring a better understanding of what was a tannery at the end of the fifteenth century. The work of tanners, from the reception of the skin to its transformation, before being sold to another specialized craftsman (shoemaker, parchment maker, saddler) requires a large supply of animal skin of all kinds (cow, sheep mainly but also game). The deeds make it possible to understand how tanners sourced, mainly from butchers, but also from other craftsmen, and at what price. The tanning work, which took several months, was organized in the city around a specific place, fed by the Loir, at the foot of the comtal castle in a dedicated street. Organized in the city, organized in their activity, tanners were gathered in brotherhood, could take apprentices, whose contracts reveal the economic constraints and the benefits that the apprentice could derive from them. They could invest in the master’s production tool. The deeds show the predominance of Châteaudun and the other villages of the county in the work of leather, craftsmanship which was not absent from the Dune countryside. The acts also make it possible to address the question of the clientele of tanners: craftsmen, merchants. What was also the connection with the county court? Finally, tanners and other leather craftsmen, massively present in the sources, are actors of the economic life of the county. By their position, their wealth, they are at the heart of community relations: lessor or creditors, they have established a network of relationships that goes beyond the simple framework of their profession.