The effects of transesterification and blend composition on the physical properties of drawn PEN/PET blend fibers were investigated. Tensile strength and modulus of PEN/PET blend fibers were increased with increasing PEN content. The X-ray diffraction patterns of blend fibers exhibited less structure development compared with PEN or PET homopolymer fibers. The transesterification reaction leads to a miscible amorphous phase with the result that all blend fibers exhibit a single glass transition temperature between those of the two homopolymers. After drawing and annealing, PET or PEN homopolymer fibers exhibited higher degree of orientation-induced crystallization than PEN/PET blend fibers.