Large-scale single-crystalline In2O3 nanowires were successfully synthesized by simply evaporating the pure indium at 950 degrees C. The as-synthesized products, characterized by XRD, SEM, and TEM, were pure, structurally uniform, and single crystalline with typical diameters of 10 to 100 nanometers and lengths of up to a few hundreds of micrometers. The growth mechanism of the nanowires also was discussed.