Background:Maintenance monotherapy with the poly(ADP-ribose) polymerase inhibitor olaparib significantly prolongs progression-free survival over placebo in patients with platinum-sensitive relapsed serous ovarian cancer, with greatest benefit seen in patients with a BRCA1/2 mutation (BRCAm). Preservation of health-related quality of life (HRQoL) is important during maintenance therapy; we evaluated the effect of olaparib on HRQoL in this Phase II trial (NCT00753545, Study 19).Methods:Patients received olaparib 400 mg b.i.d. (capsules) or placebo until progression. Patient-reported HRQoL and disease-related symptoms were evaluated using the FACT-Ovarian (FACT-O) questionnaire (completed at baseline and every 28 days until progression), the FACT/NCCN Ovarian Symptom Index (FOSI) and the Trial Outcome Index (TOI). TOI of the FACT-O was the primary measure.Results:Overall, 265 women were randomised to maintenance olaparib (n=136) or placebo (n=129). Compliance for HRQoL assessment was high (∼80% over time). Most patients in both arms reported a best response of 'no change' on TOI (81%) and other HRQoL measures. There were no statistically significant differences in time to worsening or improvement rates of TOI, FOSI and FACT-O scores in the overall, BRCAm and germline BRCAm populations.Conclusions:Maintenance treatment with olaparib was well tolerated and had no adverse impact on HRQoL in this study of patients with platinum-sensitive relapsed serous ovarian cancer who had responded to their most recent platinum-based therapy (partial or complete response). Interpretation of the HRQoL results in this population may differ from patients who have not responded to their most recent platinum-based therapy.