The deformation behavior of miscible PA6/aPA blends films under uniaxial and biaxial tensile drawing has been investigated in relation to blend composition. Whatever be the composition, the initial crystalline structure is ill-ordered and no evidence of spherulitic morphology was shown. At temperatures beyond the activation of the viscoelastic alpha relaxation, a ductility improvement upon addition of aPA has been revealed in both uniaxial and biaxial stretching. The decrease in the yield stress with increasing aPA content mainly originates from the reduction in crystal fraction. Regarding the observed evolution in ultimate drawability and strain hardening upon addition of aPA, the latter component, of the blend is considered to act as a diluent of the macromolecular network, and the experimental data are fairly well accounted for according to Graessley's theory. (c) 2006 Wiley Periodicals, Inc.