The rheological properties of the slurry that have been prepared Na-montmorillonite clay have been determined, the effects of NaCl, KCl, LiCl, CaCl2 and MgCl2.6H(2)O salts and (NaPO3)(n) polymer have also been investigated at different concentrations. The changes in rheological properties of Na-montmorillonite slurry when salts have been added to concentration have been commented. Information on the vander waals and electrostatical interaction between the colloidal clay the bentonite-water systems is given.