Non steroidal anti-inflammatory drug aceclophenac has hydrophobic and hydrophilic domain. It is sparingly soluble in water and miscible in blood due to hydrophilic nature. It exhibits analgesic, antipyretic and anti-inflammatory activities. It is best used in rheumatoid arthritis. It is inhibitor of clotting in the blood vessel, thus prevents heart attack and stroke. Leucine is an essential α-amino acid used in biosynthesis of protein and also used for muscle building. It contains α-amino group, carboxylic acid group and an isobutyl side chain. Ultrasonic study of Aceclophenac with Leucine in DMSO medium provides much useful information about the nature of their molecular interaction in a polar aqua-organic medium. In our body drug interaction with protein play very vital role in the biological process. Because of the 3D structure of protein, it is quite difficult to study its interaction with drugs in the biological system. As amino acid is a model component for protein, in this piece of work we have studied the drug amino acid molecular interaction with variation of concentration of amino acid ranging from 0.002-0.01 mol/kg and the drug concentration varies from 0.0002-0.001 mol/kg. The different acoustic parameters like adiabatic compressibility (β), intermolecular free length (L f ),acoustic impedance(z),apparent molar volume(V φ ),apparent molar compressibility (K φ ),partial molar volume (V φ o ),partial molar compressibility (K φ o ),John Dole coefficient A,B are calculated from density (ρ),ultrasonic velocities (U) and viscosity ( ) data. The parameters are calculated at 298.15K in a polar aprotic medium i.e. taking DMSO as solvent are interpreted in terms of ion-solvent, ionion and ion-dipole interactions considering the structure breaking and structure making aspects of the solvent.Copy Right, IJAR, 2017,. All rights reserved.