In this work, the effect of two dissolved inorganic salts (cadmium chloride, CdCl(2); ammonium chloride, NH(4)Cl) on the enthalpy of mixing (H(E)) of the pyridine + water binary system measured at 303.15 K using an isothermal displacement calorimeter with vapor space is investigated. Compared with the salt-free system, the addition (0.05 mass fraction) of the salts altered the magnitude of H(E) values to some extent depending on the mole fraction of x(1). The importance of the solute-solvent and solvent-solvent interactions was demonstrated from the increasing exothermic H(E) values with increasing salt concentration (0.10 mass fraction). The experimental values of H(E) were fitted into the Redlich-Kister polynomial, and the adjustable parameters obtained by the least-squares method are reported.