The number of published studies on transduction of tumor cells in vivo using recombinant adeno-associated virus (rAAV) vectors is very limited compared with those that have been published on targeting normal cells. A major reason for this can be attributed to the biology of the vector itself. AAV, being a nonpathogenic vector capable of providing transgene integration and long-term expression, is ideally suited for the correction of metabolic defects either to replace a defective protein/enzyme or to elevate their otherwise suboptimal levels in the system. However, increased understanding of both the biology of tumor progression and potential utility of AAV-based vectors suggests that this vector can also be wisely used for cancer gene therapy.