There is considerable interest in using DNA nanowires or nanotubes in a wide variety of bioelectronic applications and microcircuitry. Various methods have been developed to construct DNA nanostructures. Here, we report a novel method to construct semiconducting DNA nanowires by applying a suitable DC bias to a gold plating solution containing double-stranded DNA. The self-assembled nanowires fabricated by this method contain attached gold nanoparticles. Further, we report that the dimensions of the nanowires can be easily manipulated by altering the applied DC bias. We also confirmed the semiconducting nature of the DNA nanowires by studying their resistance-temperature behavior from 25 to 65 degrees C in a microelectrode system. These studies describe a simple process by which gold-decorated, semiconducting DNA nanowires could be created and may lead to a breakthrough in the field of self-assembly of nanometer-scale circuits. The self-assembled structures do have some similarity with tube-like structures but in the present work we are using the term 'DNA nanowires' to define the structures.