A helper dependent adenoviral vector system is provided. The subject helper dependent adenoviral vector system is made up of: (1) a "gutless" adenoviral vector that include cis-acting human stuffer DNA that provides for in vivo long term, high level expression of a coding sequence present on the vector; (2) an adenoviral helper vector that is characterized by having an adenoviral genome region flanked by recombinase recognition sites, where the helper vectors further include a non-mammalian endonuclease recognition site positioned outside of the adenoviral genome region; and (3) a mammalian cell that expresses the corresponding recombinase and endonuclease, as well as the adenoviral preterminal and polymerase proteins. Also provided are methods of using the subject systems to produce virions having the subject helper dependent adenoviral vectors encapsulated in an adenoviral capsid. In addition, kits for use in practicing the subject methods are provided.