Pharmacological studies in humans and animals have documented increased local tissue and plasma concentrations of a number of different chemotherapy agents after intra-arterial chemotherapy administration. In addition, animal studies have shown superior therapeutic efficacy using this approach. While some clinical studies of intra-arterial chemotherapy have been negative, others have supported the contention that it is advantageous in some situations. It could potentially help preserve local organ function, palliate, and prolong survival. It would have the potential of increasing cure rates only for tumors that usually kill as a result of localized disease rather than as a result of metastases. On the negative side, it has not been unequivocally proven to be superior to systemic chemotherapy administration, it is technically difficult and expensive, and it can be exceptionally toxic. Further studies are warranted, but for most tumor types, it should still be considered investigational.