The postmenopausal ovary continues to produce cysts; the prevalence in an ovarian cancer screening population approaches 18%. Yet 60% to 70% of unilocular cysts resolve spontaneously. Optimal management of an asymptomatic adnexal mass allows surveillance of women at low malignancy risk while triaging intermediate/high-risk women to surgery. Women with unilocular cysts on transvaginal ultrasound (TVS) and a normal CA-125 are monitored with repeat TVS at 3 to 6 months. Those with a complex mass <5 cm and normal CA-125 should have repeat TVS and CA-125 testing in 4 weeks. Surgery is recommended for any women with increasing morphologic complexity or a rising CA-125.