Adenoviral vector(AdV) has been the most widely used viral vector for delivering an exogenous therapeutic gene to human. As of this date, more clinical trials utilize recombinant AdV to treat cancer and monogenic inherited disease as well as vaccine applications. However, the number of clinical trials had dropped markedly following the tragic death of a patient ongoing an AdV therapy for the treatment of an ornithine transcarbamylase deficiency(OTCD). This review is an attempt to provide the information on toxicity generated by AdVmediated gene transfer. It would serve as a sobering reality to researchers and clinicians exploring the use of AdV, as to the complications involved in human application.