Transition metal dihalides have always been a challenge in both experimental and theoretical chemistry. DFT methods were used to investigate the ground and lower exited states of MnX 2 (X=F, Cl, Br, I). Several exchange-correlation potentials, basis sets and relativistic corrections were compared. We found that all MnX 2 are linear molecules with 6 Σ g + ground state. The order of the Mn-3d type MO energy levels is dσ g <dδ g <dπ g in agreement with recent theoretical results of MnF 2 and MnCl 2 and in contrast to former ligand field theory predictions. The DFT spectroscopic constants and bond lengths are in agreement with experimental values.