Aligned CdS nanowires have been prepared by de electrodeposition in porous anodic aluminum oxide template from dimethylsulfoxide solution containing cadmium chloride and elemental sulfur. These nanowires have uniform diameters of about 20 and 100 nm, which correspond to the pore sizes of the templates used, and lengths are up to tens of micrometers. HREM investigations demonstrate that these nanowires have a uniform crystalline structure of hexagonal CdS single crystal. It was proposed that the steady diffusing process of ions probably plays an important role in the growth of the nanowire by de electrodeposition.