The solid-liquid mass transfer coefficient k(L) of EGSTAR agitator, which has been practically used as a bioreactor, was measured and compared with the coefficients of some conventional impellers. Under operation conditions above the critical rotational speed for complete suspension, the solid-liquid mass transfer coefficient depends only on the power consumption per unit volume Pv regardless of the impeller geometries. The power consumption of the liquid circulation type impellers, propeller and pfaudler, for the complete suspension was lower than that of the high shear type impellers. The Maxblend impeller has the largest k(L) among the impellers used at low rotational speed. The EGSTAR agitator, in which solid particles are packed, has larger k(L) than the other impellers at low P-v.