Exogenously added granulysin was reported to kill mammalian target cells. The sites of actions and molecular mechanisms of granulysin in target cell killing, however, are presently unclear. We here examine the effects of granulysin with the target HeLa cells transiently expressed with GFP-fused 9 kDa granulysin. Endogenously expressed GFP-fused granulysin was preferentially localized in the nucleus and induced apoptotic cell death accompanying with phosphatidylserine translocation and nuclear condensation in a caspase-independent manner. These results suggest that granulysin enters the nucleus of target cells and induces apoptosis.