Abstract: The subject invention relates to a method referred to as recombination PCR (RPCR). In the method, the polymerase chain reaction is utilized to add double-stranded homologous ends to DNA. These homologous ends undergo recombination in vivo following transfection of host cells. The placement of these homologous ends, by the amplifying primers permits the rapid cloning of the desired mutant or recombinant, with a minimal number of steps and primers.