Selecting the appropriate wire alloys during orthodontic treatment requires knowledge of the biomechanical and clinical applications of various metallic orthodontic wires. Microindentation hardness testing is a convenient means of investigating the mechanical properties of a small volume of materials. The aim of this study was to apply the dynamic micro-indentation method as a simple method for determining the mechanical behavior of orthodontic wire alloys. Moreover, through this method, the effect of the indentation peak load on the mechanical behavior of orthodontic wire alloys was investigated. Four commercially available orthodontic wire alloys (stainless steel, cobalt-chromium-nickel alloy, s-titanium alloy and nickel-titanium alloy) were tested. All specimens were straight and round with a diameter of 0.018-inch. Dynamic hardness and elastic modulus of the orthodontic wire alloys under peak loads of 50, 100 and 1,000 mN were determined using a dynamic ultra-micro-hardness tester fitted with a Berkovich indenter tip. The elastic recovery on the nickel-titanium alloy was higher than on the others on unloading of microindentation load and penetration depth curves. Moreover, for all orthodontic wire alloys,both dynamic hardness and elastic modulus decreased with increasing indentation peak load. Thus, we confirmed that the hardness and elastic modulus of orthodontic wire alloys on micro indentation scales is dependent on the indentation size effect. In conclusion, the dynamic micro-indentation method is a usefultechnique for determining mechanical properties within very small areas on the surface of orthodontic wires without complex sample preparation.