Compositions and methods for modifying genetic material are provided. One embodiment provides aptamers capable of binding to a site-specific DNA binding moiety to facilitate the exchange of homologous genetic information between a donor molecule and the desired target locus (aptamer-guided gene targeting or AGT). One embodiment provides an oligonucleotide containing a aptamer, preferably a DNA aptamer at the 5′ end. The oligonucleotide also contains a region of homology, also referred to as donor DNA, to a desired nucleic acid, locus, or gene. The DNA binding moiety can be a nucleic acid, a protein, or a complex of proteins. In a preferred embodiment the DNA binding moiety is a homing endonuclease that cuts DNA to facilitate the modification of the DNA by the donor DNA.