Well-aligned ZnO nanorod arrays were prepared at different deposition times to determine the correlation between the length of the photoelectrodes and the photovoltaic performance in dye-sensitized solar cells. The length of the ZnO photoelectrode was controlled to 1.2, 2.7 and 4.0 mu m by the deposition time. The DSSCs composed of the longer ZnO nanorods showed much better photovoltaic performance due to the enhanced amount of dyes adsorbed and electron injection, as determined by the intrinsic photon-to-current efficiency and electrochemical impedance spectroscopy. The photon-to-current efficiency of the DSSC containing ZnO photoelectrode was considered with the aspect of the length of ZnO nanorods.