An experimental study has been carried out to examine the salt effect on the liquid phase equilibria for aqueous systems showing a complete miscibility in all proportions. Two model systems have been chosen, namely water-acetone and water-2 propanol with NaCl and CaCl2 as the salts. In the second theoretical part of this work, the experimental results issued from the first part have been used to calculate the interaction parameters involved in a modified version of the NRTL equation which has been extensively used for the prediction of the liquid-liquid equilibria. It has been tested with the above two systems, in presence of the salts, and encouraging results have been obtained.