We determined that a poly(ethylene terephthalate) microfiber was easily obtained by irradiating a carbon dioxide laser to an annealed fiber. The annealed fiber was prepared by zone drawing and zone annealing. First, an original fiber was zone drawn at a drawing temperature of 90degreesC under an applied tension of 4.9 MPa, and the zone-drawn fiber was subsequently zone annealed at 150degreesC under 50.9 MPa. The zone-annealed fiber had a degree of crystallinity of 48%, a birefringence of 218.9 X 10(-3), tensile modulus of 18.8 GPa, and tensile strength of 0.88 GPa. The microfiber prepared by laser heating the zone-annealed fiber had a diameter of 1.5 mum, birefringence of 172.8 X 10(-3), tensile modulus of 17.6 GPa, and tensile strength of 1.01 GPa. The draw ratio estimated from the diameter was 9165 times; such a high draw ratio has thus far not been achievable by any conventional drawing method. Microfibers may be made more easily by laser heating than by conventional technologies such as conjugate spinning. (C) 2003 Wiley Periodicals, Inc.