The interactions in aqueous solution between sodium dodecyl sulfate and the polymers methyl cellulose and polyvinyl alcohol and vinyl alcohol-acetate copolymer have been studied by viscosity measurements and by the equilibrium dialysis method. The binding data, in the form of adsorption isotherms, show the existence of a critical concentration of sodium dodecyl sulfate below which no interaction with the polymers occurs. This is taken to be indicative of hydrophobic bonding. Other features of the isotherms are explained by the increasing sodium dodecyl sulfate binding disrupting polymer aggregates which are known to be formed by methyl cellulose and vinyl alcohol-acetate copolymer in aqueous solution. In the case of the methyl cellulose sodium dodecyl sulfate system, abrupt changes in the viscosity of the solutions correlate with the binding data.