Our scanning tunneling microscopy studies show that Ag deposited: onto Si(5 5 12) and annealed to moderate temperatures (400-450 degrees C) forms well-ordered overlayer rows. These rows have aspect ratios up to 150:1 and therefore are possible candidates as "nanowires." es' the Ag coverage is increased, the rows grow in length and number until the surface forms a periodic array of:such structures at similar to 0.25 monolayer (ML). A statistical analysis of these rows reveals a linear increase in median row length as a function of coverage with a median length of 67 nm at full coverage (similar to 0.25 ML). At higher annealing temperatures (>500 degrees C) Ag continues to-form row-like structures, but the rows are wider and cause local faceting of the underlying Si substrate. We can therefore conclude that the lower temperature Ag rows are actually a metastable arrangement of the surface.