We have reported that the human malaria parasite, Plasmodium falciparum, repairs apurinic\apyrimidinic (AP) sites on DNA by a long-patch base excision repair (BER) pathway. This biology is different from that in mammalian cells, which predominantly repair AP sites by a DNA-polymerase-β-dependent, onenucleotide patch BER pathway. As a starting point for the identification and biochemical characterization of the enzymes involved in the parasite DNA BER pathway, we chose characterization of the AP endonuclease activity in a P. falciparum cellfree lysate. Evidence is provided for the presence of class II,