Ultrasonic velocity, density and viscosity have been measured for substituted heterocyclic drugs Silymarin, Rifampicin in 1, 4 dioxane at 303 k.. The measurement have been perform to evaluate acoustical parameter such as adiabatic compressibility (bs), Partial molal volume (f_v), intermolecular free length (L_f), apparent molal compressibility (f_k), specific acoustic impedance (Z), relative association (RA), salvation number(Sn), limiting apparent molal compressibility (f⁰_k), limiting apparent molal volume(f⁰_v) and their constant (S_k,S_v). The viscosity coefficient (A,B) evaluate by using johndole equation. These parameter throw the light on the solute-solvent interaction and solute-solute interaction.