A laser-heating zone-drawing and zone-annealing method using a continuous-wave carbon dioxide laser was applied to poly(ethylene terephthalate) (PET) fiber to improve its mechanical properties. The as-spun fiber was zone-drawn under a applied tension (sigma (alpha)) of 4.44 MPa at a laser power density (PD) of 6.08 W cm(-2), and then the laser-heated zone-drawn fiber was zone-annealed. The laser-heating zone-annealing was carried out in three steps: the first annealing was carried out under sigma (alpha) = 139 MPa at 4.83 W cm(-2); the second annealing was carried out under sigma (alpha) = 283 MPa at 4.83 W cm(-2), and the third annealing was carried out under sigma (alpha) = 432 MPa at 3.45 W cm(-2). The surface temperature distribution of the fiber irradiated with the CO2 laser was measured by using an infrared thermographic camera equipped with a magnifying lens. The relation between the laser power and the surface temperature of the fiber became clear in the laser-heating zone-drawing and the laser-heating zone-annealing. The fiber obtained finally had a birefringence of 0.239, a degree of crystallinity of 55%, a tensile modulus of 19.8 GPa, and a storage modulus of 25.7 GPa at 25 degreesC. In FTIR measurements, a trans conformation increased with the processing, but a gauche one decreased. The laser-heating zone-drawing and zone-annealing method was found to be effective in producing the PET fiber with high modulus and high strength.