Adenovirus (Ad) vectors have substantial potential as biological therapeutics for the treatment of human diseases. Evidence from preclinical studies and clinical trials indicated that several acquired and inherited diseases could be corrected or ameliorated with cell type-specific Ad targeting. One of the major barriers for in vivo Ad targeting is the sequestration of the blood-borne virus in the liver. Significant recent advances have been made in understanding the molecular mechanisms involved in mediating Ad sequestration in the liver. Recognizing the redundancy and synergism between the mechanisms that mediate Ad liver cell transduction and those that mediate the sequestration of blood-borne Ads in the liver creates an opportunity for the development of safe and targeted Ads for gene therapy applications.