The following project analyzes the Arian tendencies in the medieval Spanish epic, The Song of the Cid, a text that has always been considered Catholic. Historical and theological information pertinent to the subject were utilized to set forth a literary analysis of the poem. In the first chapter, the history of the Visigoths is summarized from their creation until their conversion to Catholicism in 589, during their reign in the Iberian Peninsula. The second chapter discusses Arius and his theology, mostly his stance on the hierarchy of the Trinity, in comparison to those ideas of the Catholic Church. The literary analysis takes place in the third chapter, and includes the application of the information discussed in the previous chapters to examine Arian traits in the text. In conclusion, it is established that is possible that the poem may have been influenced by this heretical Christian religion.