•Prophylactic oophorectomy can prevent small cell carcinoma of the ovary, hypercalcemic type in carriers of germline SMARCA4 mutations.•Unaffected SMARCA4 mutation carriers who desire children may be best served by oocyte cryopreservation prior to prophylactic oophorectomy.
Keywords: Ovarian cancer; Prophylactic oophorectomy; SMARCA4 mutation.