Guiding a tooth along an arch wire results in a counteracting frictional force among arch wires, bracket and ligature. This frictional forces should be eliminated or minimized when orthodontic tooth movement is being planned. The purpose of this study was to evaluate the changes of width, cross-sectional forms and surface morphologies of stainless steel wire and Elgiloy^®wire after electropolising. Experimental variables included in this experiment were arch wire materials, current, electrolyte temperature and polishing time. Wire widths were measured by micrometer and cross-sectional forms and surface morphologies were examined with optical microscope and scanning electron microscope. The results were as follows: 1. The mean and standard deviation of widths of stainless steel wire and Elgiloy^® wire varying polishing time with condition of 249A/dm^² and 20°C, 249A/dm^² and 25°C, 332A/dm^² and 20°C and 332A/dm^² and 25°C were obtained. 2. With increasing polishing time, the widths of stainless steel wire and Elgiloy^® wire became decreased proportionally. 3. The changes of widths of stainless steel wire and Elgiloy^® wire were statistically insignificant between 20°C group and 25°C group. but significant between 249A/dm^² group and 332A/dm^² group. 4. The cross-sectional forms of wire after electropolishing were not changed in stainless steel wire, and while it were changed to rounded corners in Elgiloy^® wire. 5. The surface morphologies of wire after electropolishing were scratch-absent and more smoothened both in stainless steel wire and Flgiloy^® wire.