The treatment of patients with ovarian cancer is rapidly changing following the success of poly [ADP-ribose] polymerase (PARP) inhibitors in clinical trials. Olaparib is the first PARP inhibitor to be approved by the EMA and FDA for BRCA-mutated ovarian cancer. Germ line BRCA mutation status is now established as a predictive biomarker of potential benefit from treatment with a PARP inhibitor; therefore, knowledge of the BRCA status of an individual patient with ovarian cancer is essential, in order to guide treatment decisions. BRCA testing was previously offered only to women with a family or personal history of breast and/or ovarian cancer; however, almost 20% of women with high-grade serous ovarian cancer are now recognized to harbour a germ line BRCA mutation, and of these, >40% might not have a family history of cancer and would not have received BRCA testing. A strategy to enable more widespread implementation of BRCA testing in routine care is, therefore, necessary. In this Review, we summarize data from key clinical trials of PARP inhibitors and discuss how to integrate these agents into the current treatment landscape of ovarian cancer. The validity of germ line BRCA testing and other promising biomarkers of homologous-recombination deficiency will also be discussed.