The magnetic properties of near-equiatomic Fe-Ti alloys were studied by using the electronic structure calculations. A tight-binding linear-muffin-tin orbitals (TB-LMTO) method within the local-spin-density approximation (LSDA) was employed. For the non-equiatomic alloys, a defect-specified supercell method was used. A formation of the antistructure (AS) Fe atom and its cluster plays an important role to determine the magnetic behavior of the disordered equiatomic or off-stoichiometric Fe-rich alloys. A small amount of charge transfer from the Ti to Fe atoms is crucial to the structural stability and the magnetic properties of the alloys. As the magnitude of the charge transfer increases, the magnetic moment of the Fe atom decreases. A sharp peak in the calculated density-of-states (DOS) curve just above the Fermi level grows as the Ti concentration decreases, indicating a localization of the states, which gives a better understanding of the change in physical proper-ties upon an order --> disorder transition. The sharp peak was originated from the minority spin band of the antistructure Fe atom.