Fibre-reinforced composite materials are considered to comprise three components, i.e., fibre, matrix, and the interphase. The interphase is the part of the matrix placed in the vicinity of fibre surface all along its length and has distinct properties from that of the fibre and the matrix. In the present study, it is assumed that the interphase is homogeneous and isotropic. A 2-D and 3-D finite element modelling (micromechanical modelling) of the three-phase system is conducted to predict the four damping coefficients-longitudinal, transverse, longitudinal shear, and transverse shear loss factors. Effect of interphase loss factor in the range 0.002 to 0.500 and the interphase volume fraction on the loss factors have been studied.