The cardinal Lothario’s Compendium breve has been considered for more than a century as the oldest printed book in Lyons. While older authors have sought to find older editions, none have been able to formally prove their claims. New studies on the first printed books in Lyons have made it possible to identify more precisely the city's first productions. Four editions are certainly the first books to come out of Guillaume Le Roy's workshop in Barthélémy Buyer's house. A careful examination of their characters shows that several editions can be placed before the Compendium breve. The first known book printed in Lyons then becomes a New Testament abbreviated in French. This book was a popular work at the time and Barthélémy Buyer probably wanted to sell to a bourgeois public, far from the humanist clientele of the Parisian presses. A second biblical account in French is printed shortly afterwards, proof of the success of this first edition. The choice of French was indeed revolutionary in the printing industry at that time and this language would be important in the early years of the Lyons presses. Examining the layout of these editions shows that Guillaume Le Roy reuses predefined shapes. It can also be seen that the improvement of the printer's technique makes it possible to increase by more than 20% the filling of the sheet between the first two and the last two editions.