The authors ascertained the applicability of the method proposed by Metzner to correlate agitation power for pseudoplastic liquids. For a ribbon impeller that is effective for highly viscous liquids this method is also useful. It was found by the authors that the proportionality constant between average shear rate and impeller speed for pseudoplastic liquids can be estimated by using experimental constants of the power equation for Bingham plastic liquids. Correlated results by using estimated values showed good agreement with data for various impellers. For ribbon and anchor impellers, a correlation curve similar to that for Newtonian liquids was observed throughout the whole region of Reynolds number. For turbines and paddles, however, curves for pseudoplastic liquids deviate from Newtonian in the transition region. These phenomena were explained by the spreading of the discharge flow range as in the case of Bingham plastic liquids.