The results of density functional theory (DFT) energy calculations and geometry optimizations for selected planar and ruffled conformers of nickel octaethylporphyrin (NiOEP) are reported. Calculated geometric parameters show remarkably good agreement with experimental X-ray crystallography data. The tendency C for ruffling of the porphyrin macrocycle to allow for a shorter Ni-N bond is accurately predicted by DFT calculations. Energy values indicate that ruffling of the macrocycle lowers the energy of the different conformers by about 0.2 kcal/mol.