Phi29 Polymerase is a DNA polymerase isolated from the bacteriophage phi29. The enzyme appears to be structurally similar to the E. coli DNA Polymerase Klenow Fragment, and includes a 3’-5’exonuclease activity. Phi29 Pol also acts preferentially on single stranded DNA, allowing for the novel amplification method of multiple strand displacement. Phi29 polymerase has since become an ideal tool in applications such as whole genome amplification and cell-free DNA amplification.