We have performed sensitive polarimetric radio observations with the VLA of radio galaxies embedded in extreme cooling flow clusters. High sensitivity, multifrequency maps, and maps of Faraday Rotation Measures (RMs) of 1514+0712, 1626+396, and 1603+178 are presented. 15141+0712 and 1626+396 are found to have absolute RMs in excess of 800 rad m(-2). For 1603+178, the absolute RMs are less than 100 rad m(-2), unlike 1512+0712 and 1626+396 the radio galaxy is not in the center of the cooling flow. The high RMs are likely to be produced by magnetic fields associated with the dense, hot x-ray emitting gas in the cooling flow clusters.