In this study the shear strength of filter cakes of various minerals such as dolomite, calcite, quartz and kaolin was investigated. Shear strength of the mineral filter cakes are influenced by the particle size and shape and surface tension as well as the applied pressure and saturation degree. As the particle size decreases the shear strength increases very sharply. The relation between the shear strength and the particle size has been found as: tau (shear) = K/x(0.6). The decrease of the surface tension of the mineral suspension causes to decrease of the shear strength of the cake to a large extend. (C) 2001 Elsevier Science B.V. All rights reserved.