OBJECTIVE: To evaluate whether endometriosis-associated genetic variation affects risk of ovarian cancer. DESIGN: Pooled genetic analysis. SETTING: University hospital. PATIENT(S): Genetic data from 46,176 participants (15,361 ovarian cancer cases and 30,815 controls) from 41 ovarian cancer studies. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Endometriosis-associated genetic variation and ovarian cancer. RESULT(S): There was significant evidence of an association between endometriosis-related genetic variation and ovarian cancer risk, especially for the high-grade serous and clear cell histotypes. Overall we observed 15 significant burden statistics, which was three times more than expected. CONCLUSION(S): By focusing on candidate regions from a phenotype associated with ovarian cancer, we have shown a clear genetic link between endometriosis and ovarian cancer that warrants further follow-up. The functional significance of the identified regions and SNPs is presently uncertain, though future fine mapping and histotype-specific functional analyses may shed light on the etiologies of both gynecologic conditions.