The effect of silicone softeners on hair conditioning was investigated with varied silicone treatment conditions and different thermal stress conditions. When silicon (-Si-) content was quantified from the silicone-treated hair specimens, greater contents of -Si- were observed from the hair treated with silicone softeners having amino-functionality than from that treated with polydimethylsiloxane. The adsorption of amino silicone was enhanced at higher temperature and longer treatment duration. The amino silicone softeners adsorbed more effectively on hair surface especially at lowered concentrations. Combing force of hair was lowered in greater extent when the hair specimens were treated with amino silicone softeners than with polydimethylsiloxane. The luster of hair specimens which were repeatedly treated with amino silicone softeners, however, was lowered due to more diffusion of light by the adsorption of amino silicone softeners.