IntroductionAfter premenopausal risk-reducing salpingo-oophorectomy (RRSO) to prevent ovarian cancer, the non-cancer-related morbidity and mortality may be increased if sex hormones are not replaced. Several guidelines recommend systemic hormone replacement therapy (HRT) to these women until the expected age of menopause. We aimed to study the use of HRT after RRSO. Material and methodsParticipants were 324 women after RRSO and 11 160 postmenopausal controls. A subsample of 950 controls had undergone bilateral salpingo-oophorectomy (BSO). All participants completed the same questionnaire regarding HRT use. We compared HRT use in the RRSO group with the BSO controls using logistic regression. ResultsAmong the women aged 52 years without a history of breast cancer, 51.7% of the RRSO group and 48.7% of the BSO controls reported current use of systemic HRT (odds ratio 1.13, 95% confidence interval 0.72-1.76). Among the HRT users, systemic estrogen was used by 35.1% and 58.7% in the RRSO and BSO control groups, respectively (p = 0.001). Among the women aged >52 years, 16.8% of the RRSO group and 38.4% of the BSO controls (p52 years used systemic HRT. Doctors should be aware of this practice and prescribe systemic HRT when indicated.