Cubic zinc selenide crystals were grown by vapor-phase deposition with a charge containing LiOH. The electron-paramagnetic-resonance (EPR) spectrum at 77°K consisted of an intense isotropic line at g=2.0464+/-0.0004, and a group of angular-dependent lines, each of which varied between g∥=2.072+/-0.004 and g⊥=6.1+/-0.1, depending on crystalline orientation. The intense line is attributed to the central ( 1/2 -->- 1/2 ) transition of Fe3+ in a zinc substitutional site. The less intense angular-dependent lines are attributed to Fe3+ in a crystalline field with a strong axial component. The axial component has the symmetry of a nearest-neighbor site. The large zero-field splitting due to a selenium vacancy or substitution leaves a spin doublet lowest in energy and only a transition within this doublet is observed. This leads to a single EPR line with g∥≅2 and g⊥≅6, with the parallel direction lying along a <111> direction. The four possible sites are not equivalent. This is explained on the basis of the stack-faulted nature of the crystals. The optical properties related to the imperfections giving rise to the EPR signals have also been investigated.