The effect of an applied tensile stress on the pore ordering during anodization of aluminum was studied. A regular arrangement of nanopores was observed at a relatively low external tensile stress. On the contrary, a high tensile stress completely destroys the pore arrangement on anodized surfaces. Under such conditions, huge holes and pits are formed on the surface. The arrangement of nanopores on samples anodized under applied stresses was examined by Fourier transform analysis and Delaunay triangulation and compared with nonstressed samples. The ordering of pores was found to be dependent on the applied tensile stress. The percent of defects in the triangular lattice increases with increasing applied tensile stress. This result suggests that the surface stress has to be taken into account in a future modeling of the growth of porous oxide layer on anodized aluminum. (C) 2004 The Electrochemical Society.