Background: This study attempts to ascertain a reliable cutoff size to determine whether pelvic lymph nodes are metastatic or not in ovarian cancer patients.Methods: We retrospectively reviewed 73 PET/CT scans of 52 female patients with ovarian carcinoma who underwent surgery followed by chemotherapy. The findings of contrast enhanced MDCT were interpreted by two experienced radiologists unaware of the PET/CT findings. At least two experienced nuclear medicine physicians unaware of the contrast enhanced-MDCT findings examined the PET scans in order to localize, characterize and compare these scans to co-registered PET/CT images. A comparative study was done. Lymph node sizes were recorded in short axis diameter with a significant cut off estimated at 7.5 mm. Metabolic activities of different lymph node groups were assessed and the semi-quantitative SUV was calculated. The level of SUV significance was 2.5. Significant metastatic lymph nodes were judged by the assessment of integrated PET/CT results.Results: Of the 73 scans, 47 showed significant lymph node metastases, with the following sensitivities: 75% (external iliac), 77.8% (internal iliac), and 75% (inguinal). The specificities were 84% (external iliac), 86% (internal iliac), and 54% (inguinal) with a P-value of 0.000 for the external an internal iliac groups and 0.079 for the inguinal group.Conclusion: To improve detection of malignant pelvic lymph nodes, the size threshold should be decreased to 7.5 mm.