The effect of an intense plane wave on a co-propagating weak plane wave in a lossy isotropic nonlinear medium is studied using the exact solution of H. Prakash et al.1 The presence of a plane-polarized intense beam changes the initial circular polarization of the weak beam to elliptical in general. The plane containing the direction of the major axis and the propagation oscillates about the plane of polarization of the intense beam. At the extreme positions, the elliptical polarization reduces to plane polarization and switches its handedness. For the lossless case, the plane of the major axis remains fixed at 45° to the plane of polarization of the intense beam and the polarization oscillates between circular and plane, switching the handedness when the plane polarization occurs, and there effects are periodic in distance within the medium. The presence of a circularly polarized intense beam changes the initial plane polarization of the weak beam to elliptical, whose major axis rotates in propagation. For the lossless case, the weak beam remains plane-polarized and rotates at a uniform rate in propagation. Suggestions for experimental observations of these effects are given and the values of observable quantities estimated for carbon disulfide.