Faithful replication and accurate maintenance of an organism's genetic material is essential for survival. These actions are carried out by several proteins that interact with DNA either directly or indirectly via interaction with DNA binding proteins. In eukaryotes, one protein central to both of these processes is the single stranded DNA (ssDNA) binding protein Replication Protein A or RPA. Basic biochemical information about this protein from plants is lacking. A search of the proprietary maize EST database at Pioneer Hi-bred International revealed the presence of two homologous of RPA1 and one homologue of RPA2. It is clear from previous accounts that RPA plays an important role in various pathways of DNA metabolism in eukaryotic cells. In view of the potential utility of such basic information on plant RPAs for developing plant gene targeting technology, we undertook the molecular and biochemical characterization of maize RPA.