This chapter describes the diagnosis, treatment, prognosis, and lactation for ovarian cancer in pregnancy. Various sonographic scoring systems of the adnexal mass may include features that have been associated with ovarian malignancies, such as bilaterality, heterogeneous solid component, papillary structure, septations, size >7 cm, low-resistance blood flow, and ascites. Improvement in Doppler ultrasound technology for evaluation of tumor vascularity has been used lately as a predictor of malignancy. Magnetic resonance imaging (MRI) may be used as an additional diagnostic imaging tool in more complex conditions, such as displacement of the ovaries up into the abdomen when the pregnant uterus is growing, or in metastatic disease, or in other diagnostic uncertainty. Most patients with ovarian cancer diagnosed during pregnancy have disease confined to the pelvis or abdomen. Paclitaxel-carboplatin chemotherapy until fetal maturity is the regimen of choice in ovarian cancer.