Abstract :18F-fluoro-2-deoxy-D-glucose positron emission tomography with computed tomography (FDG-PET/CT) is an important imaging modality for diagnosing many types of cancer. In gynecologic malignancies, the maximum standardized uptake value (SUVmax), one of the quantitative parameters measured on FDG-PET/CT, has been used not only for evaluating malignancy, but also for disease staging or treatment monitoring, although its prognostic impact remains controversial. This review focuses on the usefulness of SUVmax of the primary tumor on preoperative PET/CT as a prognostic indicator for patients with gynecologic cancers, and considers recent findings of our studies as well as those by others. In cervical cancer, a high SUVmax was correlated with positive lymph node metastasis and lymph-vascular space involvement in patients receiving radical hysterectomy. In endometrial cancer, a high SUVmax was also correlated with positive clinic pathological factors. Using optimal cut-off values of SUVmax, patients with a higher SUVmax showed significantly poorer overall survival and progression-free survival for both cancers. In ovarian cancer, SUVmax was useful for distinguishing malignant from borderline or benign tumors, while it had a limited prognostic role. In summary, the primary tumor’s SUVmax is a non-invasive, easily-measurable biomarker for diagnosing malignancy as well as predicting clinical outcomes of patients with gynecologic cancers.