Th e mixing performance of a BENDLEAF impeller was evaluated by the streak line visualization method developed by Inoue et al. (2009a, 2009b, 2012). The mixing performance of this impeller was different from that of other large paddle impellers developed by other Japanese companies. This impeller was able to mix highly viscous liquid with a shallower liquid depth. The optimum ratio of impeller diameter to vessel diameter d/D was about 0.6 or over, and mixing performance declined when d/D was under 0.5. The power number of the BENDLEAF impeller was correlated by the modi fied equation of the propeller and Pfaudler impellers.