A series of novel protein geranylgeranyltransferase-I (PGGTase-I) inhibitors based on a benzoyleneurea scaffold has been synthesized. Using a benzoyleneurea scaffold as a mimetic for the central dipeptide (AA), we have developed CAAX peptidomimetic inhibitors that selectively block the activity of PGGTase-I over the closely related enzyme protein farnesyltransferase. In this new class of PGGTase-I inhibitors, compound (6c) with X=L-phenylalanine, displayed the highest inhibition activity against PGGTase-I with an IC50 value of 170 nM. The inhibitors described in this study represent novel and promising leads for the development of potent and selective inhibitors of mammalian PGGTase-I for potential application as antitumor agents.