Acetone-treated fibers of poly(ethylene terephthalate) were drawn by a two-stage drawing technique: cold-drawing at 25°C followed by hot-drawing at 230°C by tensile force. The maximum achievable draw ratios (TDRs) for the treated and the untreated original fibers were 11.5 and 9.5, respectively. The highest modulus and strength of 28 and 1.2 GPa, respectively, were obtained by drawing the treated fibers with the highest TDR. These values were about 20% higher than those for the untreated drawn fibers with the highest TDR. Although annealing of the untreated drawn fibers under tensions singificantly improved the tensile modulus up to the maximum modulus for the treated drawn fibers, the tensile strength of such annealed fibers decreased remarkably due to the degradation occurring during annealing. The crystallinity of the drawn sample from the treated fiber was higher than that from the untreated fiber, leading the former to a higher structural stability against heat than the latter. These results were explained by the existence of small and/or less perfect crystals in the treated fibers induced by acetone.