We have investigated the electrical characteristics of indium-tin-oxide (ITO) films prepared by implanting tin ions into In2O3 films. In2O3 films were deposited onto a glass substrate at 250 degrees C by reactive DC magnetron sputtering in argon containing oxygen. Tin ions were implanted at an incident energy of - 190 eV. The resistivity decreased with increasing tin ion dose, and the value of 1.39 x 10(-3) Omega cm was obtained at the dose of 6.1 X 10(15) cm(-2). It was confirmed that the carrier concentration increased from 6.93 X 10(19) cm(-3) to 6.38 x 10(20) cm-3. However, the Hall mobility decreased with increasing tin ion dose. The X-ray diffraction intensity of the (440) plane decreased, and broadened with increasing tin dose. The deterioration of crystallinity of the (440) plane is considered to be the cause of the reduced Hall mobility. By vacuum annealing at 500 degrees C after tin ion implantation in order to improve the crystallinity of the (440) plane, the resistivity decreased from 1.39 x 10(-3) Omega cm to 4.46 X 10(-4) Omega cm for the In2O3 film implanted with tin ion at the dose of 6.1 x 10(15) cm(-2).