We investigated the transient bleaching and absorption of the asymmetric core/shell CdSe/CdS nanorods using the pump-probe technique. We observed ultrafast carrier relaxation and identified hole localization dynamics with 650 +/- 80 fs time constant. Upon pumping the CdSe core, we found an intense bleaching signal in the CdS spectral region, which we assigned to the delocalization of the electronic wave function on the basis of envelope-function theoretical calculations.