In this work we have investigated the effect of rheology modifiers on the rheological properties of concentrated (65 solids mass%) kaolin suspensions and six different coating colors. Measurements have been performed on kaolin-based suspensions, without rheology modifier and with either a classic cellulose thickener or associative polymers. It was noticed that suspensions containing a thickener had a much larger viscosity and storage and loss moduli than suspensions containing no rheology modifier. The enhancement of the rheological properties was found to be much more important for the suspensions containing the associative polymer. These observations have been related to steric stabilization of the suspensions, and to the occurence of entanglements and bridging when the associative polymer was used as the thickener. The influence of the thickener on the rheological properties of the coating colors was found to be similar to that observed for the concentrated kaolin suspensions.