Zinc-finger nucleases (ZFNs) are powerful tools for experimental gene manipulation. A number of recent papers have shown how this technology can be applied effectively to models of human gene therapy. Significant target genes and useful methods of ZFN delivery have been reported. Important strides have been made in minimizing toxic side effects observed with some ZFNs, which bodes well for their ultimate safety. New tools are available for the design and testing of ZFNs for new target genes. Applications of ZFNs to stem cells have been described, and genuine gene therapy trials appear to be on the immediate horizon.