A high temperature zone-drawing method was applied to a nylon 66 microfiber, obtained by using CO2 laser-thinning, to develop its mechanical properties. The microfiber used for the high temperature zone-drawing was prepared by winding at 150 m min(-1) the microfiber obtained by irradiating the laser at 4.0 W cm(-2) to an original fiber with a diameter of 50 mu m, and had a diameter of 9.6 mu m and a birefringence of 0.019. The high temperature zone-drawing was carried out in two steps; the first drawing was carried out at a temperature of 230 degrees C at supplying and winding speeds of 0.266 and 0.797 m min(-1), the second at 250 degrees C at supplying and winding speeds of 0.266 and 0.425 m min(-1), respectively. The diameter of the microfiber decreased, and its birefringence increased stepwise with the processing. The high temperature zone-drawn microfiber finally obtained had a diameter of 4.2 mu m, a birefringence of 0.079, total draw ratio of 4.8, tensile modulus of 12 GPa, and tensile strength of 1.0 GPa. The wide-angle X-ray diffraction photograph of the drawn microfiber showed the existence of highly oriented crystallites. (c) 2006 Wiley Periodicals, Inc.