The application of an external magnetic field resulted in the formation of self-aligned metallic nickel nanowires of about 50 nm in diameter. Nickel particles were prepared in the absence of a magnetic field to better illustrate the structure directing role of the magnetic field. Physical properties of the nickel nanochains were examined by scanning electron microscopy (SEM), transmission electron microscope (TEM), X-Ray diffraction (XRD), and thermogravimetric analysis (TGA) methods. This study provides a simple method to prepare Ni nanowires in large scale which broads their practical applications.