Thin films of Y 3− x Bi x Fe 5 O 12 ( x ≤ 0.3 ) have been grown on Gd 3 Ga 5 O 12 and Sm 3 Ga 5 O 12 substrates by liquid phase epitaxy. Faraday rotation and optical absorption measurements between 0.7 and 0.4 micron are reported. Near 0.5 the FR has a large negative value of −3 degrees/micron for x = 0.26 as compared with +0.3 degrees/micron for YIG. Both the optical absorption and the figure of merit (rotation/absorption) are higher for the Bi containing garnet films. The promising properties of these materials for magneto‐optic applications are discussed.