A rheology model has been developed for the prediction of silica suspension viscosity. This model can be applied for the prediction of non-Newtonian viscosity of agglomerative suspensions with particle size distribution. Since the model assumes that the particle shape is spherical, mono-modal spherical silica particles is used to prepare concentrated suspensions. Viscosity measurement results have proved that the present model is able to predict the non-Newtonian suspension viscosity under steady simple shear flow conditions. The applicability of the present model must be checked for the suspensions with particle size distribution in the future.