Abstract: Cell-penetrating peptides (CPPs) have been used to overcome the lipophilic barrier of the cellular membranes and deliver large molecules and even small particles inside the cell for their biological actions. CPPs are being used to deliver inside cell a large variety of cargoes such as proteins, DNA, antibodies, contrast (imaging) agents, toxins, and nanoparticular drug carriers including liposomes. In this paper, we have reviewed the delivery of different molecules and particles mediated by TAT, Antp, VP22, and other CPPs as well as potential applications of these delivery systems in different areas of vaccine development, cancer immunotherapy, gene delivery, and cellular imaging. [Copyright &y& Elsevier]