Zinc nitride (ZnN) films were prepared by electron beam evaporation technique. The effect of heat treatments on the structural and optical properties of these films were studied. The as-deposited films show amorphous structure and some peaks which are related to Zn3N2 and ZnO can be observed for annealed films. The study of the optical gap shows that these films have direct optical band gap about 3.2 eV at temperature 350 ◦ C. At high temperature, the ZnN films become more opaque and resistive. Other optical parameters such as refractive index, extinction coefficient and dispersion parameters were investigated as a function of annealing temperature.