The seed-mediated growth method is the most common and achieved method for synthesizing high-quality gold nanorods. A typical growth protocol involves the addition of citrate-capped gold nanospheres, served as seeds, to the bulk HAuCl4 growth solution. The growth solution is obtained by the reduction of HAuCl4 with ascorbic acid in the presence of cetyltrimethylammonium bromide (CTAB) surfactant and silver ions. Longer nanorods (up to an aspect ratio of 25) can be obtained in the absence of silver nitrate by use of a three-step addition procedure. In this protocol, seeds are sequentially added to growth solution in order to control the rate of heterogeneous deposition and thereby the rate of crystal growth.