ABSTRACT:We propose an extension of the modified simplified-improved-binaryencounter dipole (MRIBED) model (Uddin et al., Phys Rev A 2005, 72, 032715), incorporating both the ionic and relativistic corrections, to investigate the K-shell ionization of atomic targets with atomic numbers Z ϭ 1 Ϫ 92 for incident energies up to 2 GeV. We also revisit our earlier models, MBELL (Haque et al. Phys Rev A 2006, 73, 012708) and MKLV (Uddin et al. Eur Phys J D 2006, 37, 361), for the K-shell ionization at these ultra-relativistic energies. The results from our extended version of MRIBED, MBELL, and MKLV models agree well with the experimental findings.