We have developed an empirical many-body potential and used it to investigate the dynamical behaviours of fee Ni-24%Fe alloy. The new many-body potential contains both two- and three-body atomic interactions. The two-body potential is expressed by the modified form of the generalized Morse potential and the three-body potential is developed based on the new two-body model potential. The parameters defining the many-body potential for Ni and Fe were computed following a procedure similar to the method defined by Akgun and Ugur for fee structure at the lattice constant of the alloy. The radial, tangential and three-body force constants of the alloy were calculated by the concentration averages of the computed force constants of the component metals. Finally, the phonon frequencies of the alloy along the principal symmetry directions were computed using the calculated two- and three-body force constants. The theoretical results were found to be in good agreement with the corresponding experimental values.