This study delves into the syntagmatic composition of the medieval epic the Cantar de Mio Cid. The detailed structural analysis of the Cantar de Mio Cid reveals that it consists of nineteen tales and that the functions contained in each of those nineteen tales almost invariably succeed one another in the same diachronic order as those prescribed by Vladimir Propp in his Morphology of the Folktale, relations that, to date, have escaped the attention of both Spanish medieval scholars and literary critics alike. The importance of the above finding is that the present morphological analysis of the Cantar de Mio Cid firmly links the structure of the Spanish epic to that of the structure of the folktale. The implication of the latter point is both clear and significant in that it ties the structure of the Cantar de Mio Cid to that of the fairytales studied by Propp in his Morphology and reveals that the two are intimately related to each other by the fact that they are rooted in the folk fable. The latter phenomenon leads to the following original finding of this book, namely, that not only the Cantar de Mio Cid but possible all folk epic diageses constitute extended fairy tales