The ability to engineer precise genetic modification of human stem cells offers the promise to extend the range of their potential therapeutic application. This possibility is now being realized via the use of zinc finger nucleases (ZFNs). ZFNs are customizable, sequence-specific endonucleases that can be designed to introduce a discrete cleavage event at any user-chosen location within the stem cell genome. This presentation will describe our progress in translating ZFN-modified hematopoietic stem/progenitor cells (HSPCs) from concept to clinic, focusing on preclinical proof-of-concept studies supporting the development of autologous, genome-edited CD34+ HSPCs as potential treatments for both HIV/AIDS as well as certain monogenic diseases of the blood, such as β-thalassemia. DisclosuresUrnov:Sangamo BioSciences: Employment.