In this study, the effect of crystallinity of grain and grain boundaries in electroplated gold thin-film interconnections on their electromigation (EM) resistance was investigated experimentally. The activation energy in Black's equation was evaluated by accelerated EM test and Arrhenius plot as a function of the crystallinity of the interconnection. The activation energy in the electroplated gold thin-film interconnection was increased from 0.54 to 0.61 eV by improving the crystallinity due to the annealing at 400°C after electroplating. The lifetime of the interconnection was estimated by using the evaluated activation energy. The estimated result showed that the lifetime of the interconnection annealed at 400°C was about 20 times longer than that of as-electroplated interconnection. Therefore, the control of the crystallinity is indispensable for improving the reliability of electronic devices.