Since it was first demonstrated that recombinant adenovirus (Ad) vectors could be generated by inserting foreign genes into Ad genomes, they have been extensively used as eukaryotic expression vectors and therapeutic gene delivery vehicles. Originally, Ad vectors were based on the human Ad5 serotype and while most currently used Ad vectors are still based on Ad5, recent research has highlighted a series of problems that limit the efficacy and safety of these vectors. To circumvent the problems associated with Ad5-based vectors, new vectors have utilized various Ads of both human and nonhuman origin. In this review we introduce the recent advances made in the development of non-Ad5-based vectors.