It is time to stop unjustified oophorectomies Walter A. Rocca, MD, MPH Mayo Clinic, Rochester, Minnesota, USA Context: I propose that bilateral oophorectomy should not be considered a routine preventive intervention in the majority of women at average risk of ovarian cancer. Objective: In 2016, a first study showed that the premature loss of ovarian function may lead to increased DNA methylation, a biological marker of accelerated aging (Levine et al., 2016), and a second study showed an association between bilateral oophorectomy performed before menopause and the rate of accumulation of multimorbidity (Rocca et al., 2016). However, it remains difficult in a non-experimental setting to definitively test whether accelerated aging leads to symptoms that prompt bilateral oophorectomy, or whether bilateral oophorectomy prompts hormonal changes leading to accelerated aging (cause-effect uncertainty). Methods: In 2017, we addressed the cause-effect uncertainty with new analyses restricted to women who did not have any of 18 chronic conditions at baseline (Rocca et al., 2017). The Rochester Epidemiology Project records-linkage system was used to identify 420 premenopausal women who underwent bilateral oophorectomy for a non-cancerous condition from 1988 to 2007 in Olmsted County, MN (age <46 years). These women were age matched to 592 referent women (±1 year) who had not undergone bilateral oophorectomy. Results: After adjustments for several possible confounding variables present at baseline, women who underwent bilateral oophorectomy experienced an accelerated rate of accumulation of 18 chronic conditions considered together (HR=1.24; 95% CI=1.12-1.37; p <.001). Findings did not vary by surgical indication for the oophorectomy. Conclusions: Current biomarker data and clinical evidence suggests that bilateral oophorectomy is causally linked to accelerated aging, and should not be performed in women at average risk of ovarian cancer.