IMPORTANCE OF THE FIELD: Tumor associated antigens (TAAs) offer specific targets for developing cancer immunotherapies. In particular, viral vectors encoding transgenic TAAs have been used in recent vaccination strategies. Wilm's Tumor gene (WT1) is a robust TAA which is overexpressed in many malignancies and has been recently used to develop a novel recombinant adenovirus (Ad-WT1) for antitumor immunotherapy. AREAS COVERED IN THIS REVIEW: The lines of evidence over the past two decades leading to the development of Ad-WT1 immunotherapy are reviewed, including preclinical studies and clinical trials using WT1-based vaccines and TAA-expressing adenoviral vectors for antitumor therapy. WHAT THE READER WILL GAIN: The fundamental immunogenic properties of WT1-based vaccines are detailed, as well as the recent progress in using adenoviral vectors for eliciting a TAA-specific immune response. The reader will also gain an understanding of the evidence supporting Ad-WT1 antitumor therapy in vivo. TAKE HOME MESSAGE: Ad-WT1 elicits a potent CD4(+) and CD8(+) T cell immune response and can effectively inhibit tumor growth in vivo, thus making it an important potential cancer therapy worthy of future investigation.