‘Now Simon's mother-in-law was in bed with a fever, and they told him about her at once. He came and took her by the hand and lifted her up. Then the fever left her, and she began to serve them.’1 Does the author of the Gospel of Mark believe that the fever in Mark 1.30 is demonic? Or does he trace it to the power of God? It is also possible that he looks at the fever as a result of medical causes. It could be the case he author has no clear perception of the cause of the fever. In the Greco-Roman culture of Mark's audience, the fever could be seen as the result of medical, astrological, divine, or demonic causes. This set of facts will be established below. The text in Mark can then be read in four different ways depending on the understanding of fever that the scholar chooses to adopt. Given the cultural possibilities for understanding fever, Mark's text takes on a certain ambiguity. The ambiguity should be carefully upheld in light of recent attempts to precisely identify the Markan etiology of the fever.