Such is the assessment of Alain Chartier's verse compositions by Castilian writer and bibliophile Íñigo López de Mendoza, marquis of Santillana and one of the most prominent literary figures of mid fifteenth-century Iberia. In his Prohemio e carta (an epistolary prologue to a collection of his poems circa 1449), Santillana narrates a translatio studii of sorts by briefly reviewing great poets and their works, from the ancient Greeks to his contemporaries. Chartier occupies a place of honor in the French section, next to Guillaume de Lorris, Jean de Meun, Guillaume de Machaut, and Oton de Granson, and he is the only one who merits a detailed mention of his poetic works. We know that Santillana possessed a codex containing two of the poems he mentions, the Debat Reveille matin and La Belle Dame sans mercy, but his choice of Chartier's works in the quotation above also points to the Marquis's probable contact with additional manuscripts, since he mentions poems that are not by the Dauphin's secretary but were often copied next to the BDSM and attributed to Chartier. Moreover, some scholars have made a case for Chartier's influence on Santillana's own poetic production.

The direct relationship between Santillana and Chartier's verse work has diverted critical attention from the broader circulation of the French writer's prose in Castile. However, there exists clear proof of the Castilian diffusion of at least one of Chartier's prose treatises: the Quadrilogue invectif (1422), translated at some point between 1432 and 1458. The translation remains very faithful to Chartier's text and employs a highly literal style.