Background/Purpose: Analyse the outcomes of stages I–III inoperable endometrial cancer (IEC) patients treated with external-beam-irradiation (EBRT) and 3D-image-guided-brachytherapy (IGBT). Material and Methods: Medical records of IEC patients receiving EBRT + IGBT in eight European and one Canadian centres (2004–2019) were examined, including: pelvic ± para-aortic EBRT and lymph node boost; anaesthetic procedure, applicators, BT-planning imaging, clinical target volume (CTV), brachytherapy schedule, and EQD2 to the CTV_{(α/β=4.5Gy)} and D2 cm³_(α/β=3Gy) for organs at risk. Complications are evaluated using CTCAEv4 scores. The 2- and 5-year survival probability according to stages was estimated (cancer-specific survival (CSS), disease-free survival (DFS), local relapse-free survival (LRFS), loco-regional relapse-free survival (LRRFS), and distant metastasis-free survival (DMFS)). Statistics: descriptive analysis and the Kaplan–Meier method. Results: 103 patients (stages: I-44, II-14, III-44) were included. Median follow-up: 28 months (7–170). All patients received pelvic ± para-aortic EBRT. Median D90-EQD2_(α/β=4.5) to the CTV:73.3 Gy (44.6–132.7), 69.9 Gy (44.7–87.9 and 75.2 Gy (55.1–97) in stages I, II, and III, respectively. Thirty patients presented relapse (stages: 10-I, 3-II, 17-III): 24 uterine (stages: 7-I, 3-II, 14-III), 15 nodal (stages: 4-I, 1-II, 10-III), and 23 distant (stages: 6-I, 2-II, 15-III). Five year CSS was 71.2% (stages: 82%-I-II and 56%-III) and DFS, LRFS, LRRFS, and DMFS were 55.5%, 59%, 72%, and 67.2%, respectively. Late G3-G4 complications (crude): 1.3% small bowel, 2.5% rectum, and 5% bladder. Conclusion: In stages I–III of the IEC, EBRT + IGBT offer good 2- and 5-year CSS of 88.7% and 71.2%, respectively, with the best outcomes in stages I–II. Prospective studies are needed to determine how better outcomes can be achieved.