Endometriosis, a chronic inflammatory condition affecting 10% of biological women, is widely understudied and particularly overlooked in later life. Discussions surrounding endometriosis predominantly centre on medical gender bias during reproductive years, with limited attention to intersecting factors of discrimination and the impact of ageism on affected individuals. As endometriosis is framed as a disease of reproductive age, research is lacking when it comes to the effects of the illness on the older population. Symptoms in (post)menopausal individuals are frequently misattributed to (...) other ailments due to ageist and sexist preconceptions, leading to prolonged diagnoses and mistreatment. This is a social justice issue in which age and sex contribute to the discrimination of a certain population – namely older biological women living with endometriosis. In this paper, we approach this issue from the perspective of epistemic justice. The experiences of the affected persons are shaped by a lack of knowledge about endometriosis among both the healthcare personal and the affected person, as well as a lack of acknowledgement and consideration of the persons experiences. Using the lens of epistemic justice, we develop an analytical model to understand the intersection of age and gender in the experiences of endometriosis patients. This article contributes to ongoing debates on epistemic injustice and intersectionality within medicine and healthcare, offering an analytical model that connects the critical approaches of epistemic injustice and intersectionality to address health injustice. Ultimately, this work advocates for a comprehensive, lifespan approach to endometriosis that acknowledges and addresses intersecting forms of discrimination. (shrink)