Polymer latexes have many industrial applications and are considered as models of colloids. The DLVO theory has been widely used to describe the colloidal stability. The adsorption of Ni2+ and Fe3+ cations on polyvinyl acetate latex particles in the presence of counterions, and the colloidal stability of the system were studied. The obtained results indicate that Ni2+ or Fe3+ cations were adsorbed on the latex particles’ hairy layers, which also helped to prevent latex coagulation. The stability of the PVAc latex within highly concentrated ionic media shows a deviation from the behavior described by the classical DLVO theory.