The seven Cantari di Lancillotto, transmitted by the single manu- script Laurenziano Pluteo 78.23, represent a rewriting in ottava rima of the Old French prose romance La mort le roi Artu and show, in ad- dition to many of the formal features characterizing the cantari genre, a quite unusual systematic reliance on a written source, most likely an Old French version of the romance circulating in Italy. The paper aims to take a closer look at the relationship between the two texts, rst of all putting in evidence how the anonymous author approached such a long and complex prose text in order to t the narrative material into the different social context and literary framework of the cantari gen- re and, subsequently, underlining the syntactical and lexical elements in common between the Old French prose text and its “adaptation” in ottava rima.