Abstract: Sound velocity, density and viscosity values have been measured at 303 K in the ternary system of aniline+ethanol+toluene. From these data, acoustical parameters such as adiabatic compressibility, free length, free volume and internal pressure have been estimated using the standard relations. The results are interpreted in terms of molecular interaction between the components of the mixtures. Observed excess values in all the mixtures indicate dipolar and weak dispersive type interactions exist in the system.