Abstract: Nanowires are widely recognized as key elements in the development of futuristic nanoscale devices of nanoelectronics, optoelectronics and nano-electro-mechanic systems. Lithographic fabrication, however, faces increasing difficulties in the realization of continuously miniaturized features. The “Bottom-up” approach is a promising successor to lithography for fabrication of nanostructures. DNA is a natural template for nanowire assembly. The linear polynucleotide chain has a width of 2 nm and a length of 0.34 run per nucleoside subunit. One-dimensional magnetic Co and Ni nanoparticles have been assembled in-situ for the first time by use of single DNA molecules as templates. Target metallic nanowires that are 10–30 nm thick have been grown on DNA templates by catalysis of 2–3 nm Pd nuclei in a three-step electroless plating process. Au microelectrodes have been designed, fabricated, and used to assemble conductive Pd nanowires and DNA-templated Au nanowires. The wires have been characterized with various physical methods. Various methods have been utilized to orient DNA molecules on solid supports and between electrodes. In addition, a novel approach of pre-nucleated growth on designed and synthesized single-stranded DNA templates has been proposed to assemble highly uniform and conductive nanowires by metallic nanoparticle deposition. This research has resulted in the development of novel approaches to fabricate magnetic nanowires, study fundamental aspects of DNA molecule-based nanoassembly, and utilize standard tools of molecular biology in nanotechnology.