A model for collisional luminescence depolarization of molecular complexes with internal rotation at an arbitrary ratio of moments of inertia of the moving parts was developed. Theoretical expressions for the luminescence anisotropy in the J-diffusion model and generalizations of the Levshin–Perrin relations were obtained. It was shown that the luminescence depolarization of the complexes depended strongly on the ratio of the moments of inertia of the complex parts, the orientation of the rotation axes, and the directions of the transition moments.