Dysgerminomas are rare ovarian tumors that occur predominantly in young women. They arise from the undifferentiated primordial germ cells. Characteristic imaging findings include multilobulated solid masses with prominent fibrovascular septa in CT scan. However, the characteristic features are not always presented and the equivocal regional lymph nodes make the diagnosis more difficult. FDG PET/CT is useful in differentiating between malignant and benign ovarian tumors and has high specificity in detecting metastatic lymph nodes. It has considerable impact on patient diagnosis and management. We hereby present a case of ovarian dysgerminoma. The FDG PET/CT findings of the tumor and regional lymph nodes are disscussed.