New resonances in frequency space for the non-degenerate four-wave mixing are presented in this work, where the resonances peaks for a two-level molecular system with non-zero permanent dipole moments are expressed in analytical closed form for the Fourier components of the most important contributions of the macroscopic induced polarization. The topological characteristics of these new resonances are a consequence of neglecting the rotating-wave approximation. © 1998 Elsevier Science B.V.