The Applicability of the dilatancy model (Ookawara and Ogawa, 2000), which is based on the assumption that momentum flux is increased by particle collision, to suspensions in shear-thinning medium was examined experimentally. Aqueous solutions of 0.04, 0.06, 0.08 and 0.10 wt% polyacrylamide were prepared as suspending media. It was confirmed that these media showed shear-thinning properties and could be expressed by a power-law model in the shear rate range of 100-1,000 s(-1). The indices of the model were 0.804, 0.759, 0.730, and 0.697, respectively. Suspensions of 10, 20 and 30 vol % polymethylmethacrylate particles, whose average diameter is 7 mum and density is 1,190 kg/m(3), were prepared in these media. It was shown that the flow curves of these suspensions approached Newtonian with the increase of particle concentration and power-law model could not be applied. Therefore, the simultaneous application of classical suspension viscosity equation and the dilatancy model to these suspensions was examined. It was shown that a polynomial of degree 2 of the volume fraction and the dilatancy model could predict the flow curves of suspensions from the flow curves of media and particle concentrations.