Gene therapy has the potential to provide highly selective, curative cancer treatments without inducing systemic toxicity. Adenoviral vectors have been extensively used for cancer gene therapy because of their relatively high efficacy of gene transfer. However, gene transduction to cancer cells is limited by the necessity of using adenoviral type 5 vectors. This is because these vectors have a low transduction efficiency due to weak expression of the adenovirus receptor, coxsackie-adenovirus receptor (CAR), on cancer cells. Moreover, there may be side-effects to the treatment as normal cells also express CAR. In order to eradicate cancer cells without side-effects, the development of a targeting-vector is therefore crucial. In this review, the recent targeting strategies of adenoviral vectors for cancer gene therapy are summarized.