DNA primases are essential for the initiation of DNA replication and progression of the replication fork. Recent phylogenetic analyses coupled with biochemical and structural studies have revealed that the arrangement of catalytic residues within the archaeal and eukaryotic primase has significant similarity to those of the Pol X family of DNA-repair polymerases. Furthermore, two additional groups of enzymes, the ligase/primase of the bacterial nonhomologous end-joining machinery and a putative replicase from an archaeal plasmid have shown striking functional and structural similarities to the core primase. The promiscuous nature of the archaeal primases suggests that these proteins might have additional roles in DNA repair in the archaea.