In this study, previously reported results on the magnetic coupling constants of CuF2 are completed. The most prominent coupling constants are determined qualitatively by UHF calculations on the 3D periodic system and more quantitatively through accurate quantum chemical cluster calculations that explicitly include electron correlation effects. The magnetic ground state of CuF2 thus predicted is in agreement with experimental findings. For the dominant coupling constant, J(2), the value - 130 K is obtained. This value is about five times larger than the CASCI or the UHF values themselves, showing the importance of dynamical correlation effects.