Ovarian cancer continues to present a significant health challenge with little progress being made over the past two decades in reducing the incidence and mortality. More recently, novel therapeutics have emerged as a potential way of improving outcomes for women with advanced ovarian cancer who harbor mutations in genes involved in homologous recombination (HR), most notably BRCA1 and BRCA2. In the United States, Olaparib, a PARP inhibitor, has been recently approved for ovarian cancer patients treated with three or more lines of prior chemotherapy who harbor germline mutations in BRCA1 or BRCA2. As a caveat to Olaparib's FDA approval, BRACAnalysis CDx(®) was approved as a companion diagnostic test for women with ovarian cancer to determine their BRCA1/2 mutation status and eligibility for treatment. This review article will provide essential background information on hereditary breast and ovarian cancer (HBOC), describe the therapeutic mechanism of PARP inhibitors, and will chronicle the current and emerging homologous recombination deficiency (HRD) assays and their associated patents.