Endometrial cancer (EC) is the most common gynaecological cancer in developed nations and its incidence is rising. As a direct consequence, more women are dying from EC despite advances in care and improved survivorship. There is a lack of research activity and funding, as well as public awareness about EC. We sought to engage patients, carers and healthcare professionals to identify the most important unanswered research questions in EC. The priority setting methodology was developed by the James Lind Alliance and involved four key stages: gathering research questions; checking these against existing evidence; interim prioritisation; and a final consensus meeting during which the top ten unanswered research questions were agreed using modified nominal group methodology. Our first online survey yielded 786 individual submissions from 413 respondents, of whom 211 were EC survivors or carers, and from which 202 unique unanswered research questions were generated. 253 individuals, including 108 EC survivors and carers, completed an online interim prioritisation survey. The resulting top 30 questions were ranked in a final consensus meeting. Our top ten spanned the breadth of patient experience of this disease and included developing personalised risk scoring, refining criteria for specialist referral, understanding the underlying biology of different types of EC, developing novel personalised treatment and prevention strategies, prognostic and predictive biomarkers, increasing public awareness and interventions for psychological issues. Having established the top ten unanswered research questions in EC, we hope this galvanises researchers, healthcare professionals and the public to collaborate, coordinate and invest in research to improve the lives of women affected by EC.