The question of the relation between reason and revelation existed in the most ancient periods of history of human thought. Like others, Muslim philosophers were also preoccupied with such a question. The present article studies Farabi and Averroes's opinions (about this issue) and compares them with each other. The comparison shows that they, having their own original ideas, were present at two critical moments; when Islamic philosophy was on the rise and when Islamic philosophy was revived (after it was attacked by al-Ghazzali). Both philosophers agree that reason and revelation are in harmony with each other, for they speak of the same reality with this minor difference that Averroes admits the apparent difference between them and attempts to resolve it through the science of interpretation whereas according to Farabi there is no difference at all between the two for the audience of philosophy is quite different from that of religion. Referring to the works of these two philosophers, this paper studies their most important ideas and compares them with each other