Measurements have been taken of the relationship between flow rate and pressure drop for non-Newtonian fluids in two- and three-phase fluidized beds and the minimum fluidization velocities have been determined. Aqueous solutions of carboxymethyl cellulose and xanthan gum have been used as the non-Newtonian liquids. The measurements covered Reynolds numbers at minimum fluidization from 0.0337 to 540 and flow indices in a power-law model from 0.489 to 1. The minimum fluidization velocity decreased with an increase in the gas velocity and the magnitude of this decrease became smaller as particle size decreased. The increase of the viscous non-Newtonian flow behaviour or pseudoplasticity led to a decrease of the minimum fluidization velocity. The results for the minimum liquid fluidization velocity for two-phase systems have been examined using the correlation based on the free-surface cell model. The predicted minimum fluidization velocities were in reasonable agreement with the experimental data for non-Newtonian liquid-solid two-phase systems over the whole Reynolds number region.