Despite increased recognition of the value of including patient-reported outcomes (PROs) as important end points in phase III clinical trials, there has been a lack of pre-specified PRO hypotheses and shortcomings with the analyses and interpretation of PROs in many ovarian cancer trials. This paper discusses and provides examples of the so-called lost opportunities in ovarian cancer trials. These include: (i) no clear pre-specified PRO hypotheses; (ii) PRO end points not included; (iii) insensitive PRO end point selection; (iv) collection of poor-quality PRO data not suitable for analysis; (v) differences in PROs between treatment arms ignored; and (vi) poor reporting quality. We can learn from the past and with relatively little additional effort, improve the collection and interpretation of PRO data in future ovarian cancer trials. The importance of doing so is underpinned by recent initiatives to improve the standard and usefulness of PRO data in clinical trials. These include the Food and Drug Administration (FDA) Guidance for PROs to support labelling claims, the European Society for Medical Oncology Magnitude of Clinical Benefit Scale (ESMO MCBS), the International Society for Quality-of-Life Research PRO reporting guidance and the Consolidated Standards of Reporting Clinical Trials (CONSORT)-PRO-extension statement which includes a checklist of recommended items to include in PRO sections of trial protocols. Promoting the importance of hypothesis-driven PROs in ovarian cancer clinical trials will lead to improvements in the design of these trials and the interpretation of their results.