Highly uniform Ni nanowire arrays have been fabricated using electrochemical deposition into the nanochannels of porous anodic aluminum oxide (AAO) template. X-ray diffraction pattern shows that the deposited material is Ni. Field emission scanning electron microscope results indicate that the pores of AAO template are highly uniform and all the pores are filled with Ni nanowires. Transmission electron microscope observations demonstrate that the diameter of the nanowires is about 60 nm which is the same as the template used. The electron diffraction patterns and high-resolution transmission electron microscope results show that the Ni nanowires are single crystals. Magnetic measurements of the nanowire arrays show that the magnetic coercivity for the applied field parallel to the nanowires is larger than that for the applied field perpendicular to the nanowires. (C) 2003 Elsevier B.V. All rights reserved.