In this paper we present a method to compute ionization rates induced by relativistic electron precipitation with arbitrary incidence. Atmospheric ionization for monoenergetic (>100keV) relativistic electron precipitation including explicitly ionization by Bremsstrahlung radiation is considered. Two peaks of energy deposition in the atmosphere can be identified. The first ionization peak is related to direct ionization of primary relativistic electrons, while the second corresponds to Bremsstrahlung radiation. The ionization rates are presented us Look-up Tables for vertical, isotropic and angular distributions for 15°,30° and 45° angles of electron incidence. A computation algorithm is provided to compute ionization for an arbitrary angular distribution of precipitation electrons.