OBJECTIVE The goal of this study was to evaluate the combination of sentinel lymph node (SLN) mapping and F-fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) scan in detection of lymph node involvement in patients with endometrioid endometrial cancer (EEC). METHODS/MATERIALS Ninety-five patients with EEC who had preoperative PET/CT imaging and underwent SLN mapping were retrospectively analyzed. Methylene blue dye was used and injected to the cervix at 3- and 9-o'clock positions (a total of 4 mL). Pelvic lymphadenectomy was performed on all of the patients after SLN mapping. If the SLN was negative in the initial hematoxylin and eosin staining, an ultrastaging study was performed for the SLNs. RESULTS Sentinel lymph nodes were detected in 77 (81.1%) of 95 patients, with a mean of 2.95 SLNs. There was only 1 case (1.4%) with a positive SLN in the intraoperative frozen section examination in those patients with negative PET/CT findings and in whom SLNs were detected (n = 70). Among the remaining 69 patients with negative preoperative PET/CT findings and negative frozen section results for the SLNs, there were 2 patients with SLN involvement in the final ultrastaging pathology. In the patient-based analyses, the sensitivity, specificity, and positive and negative predictive values of the PET/CT and SLN frozen section were 33%, 100%, 100%, and 97.1%, respectively. CONCLUSIONS As no metastases in the nonsentinel pelvic lymph nodes were found in patients with EEC who had both negative PET/CT findings and frozen section results of the SLNs in both hemipelvises, we suggest using both methods to reduce the incidence of unnecessary systematic lymphadenectomy.