Poly(ADP-ribose) polymerase (PARP) is believed to play a critical role in the detection of DNA damage and initiation of DNA repair. Although inhibition of PARP has received increasing attention for therapeutic application in a wide variety of acute and chronic diseases, most of the current clinical data surrounding PARP inhibition is in the field of oncology. At least eight different PARP inhibitors have been, or are expected to be evaluated in the clinical oncology setting in 2007 and 2008. This review summarizes the most recently presented or published data on these therapeutic molecules, and discusses how these drugs may continue to be developed in the future.