Gene targeting is a powerful tool for functional gene studies. However, only a handful of reports have been published describing the successful targeting of genome sequences in model and crop plants. Gene targeting can be stimulated by induction of double-strand breaks at specific genomic sites. The expression of zinc finger nucleases (ZFNs) can induce genomic double-strand breaks. Indeed, ZFNs have been used to drive the replacement of native DNA sequences with foreign DNA molecules, to mediate the integration of the targeted transgene into native genome sequences, to stimulate the repair of defective transgenes, and as site-specific mutagens in model and crop plant species. This review introduces the principles underlying the use of ZFNs for genome editing, with an emphasis on their recent use for plant research and biotechnology.