Many GTPases such as Ras, Ral and Rho require post-translational farnestylation or geranylgeranylation for mediating malignant transformation. Dual farnesyltransferase (FT) (FTI) and geranylgeranyltransferase-I (GGT-1) inhibitors (GGTI) were developed as anticancer agents from based on an ethylenediamine scaffold. On the basis of a 4-fold substituted ethylenediamine scaffold, the inhibitors are structurally simple and readily derivatized, facilitating extensive structure-activity relationship studies. The most potent inhibitor is compound exhibited an in vitro hFTase IC50 value of 25 nM and a whole cell H-Ras processing IC50 value of 90 nM. Several of the inhibitors proved highly selective for hFTase over the related prenyltransferase enzyme geranylgeranyltransferase-I (GGTase-I). A crystal structure of an inhibitor cocrystallized with farnesyl pyrophosphate in the active site of rat FTase illustrates that the para-benzonitrile moiety is stabilized by a π-π stacking interaction with the Y361β residue, suggesting an importance of this component of the inhibitors.