PurposeAnalyse the impact of different prognostic factors on G2-late vaginal complications after vaginal brachytherapy (VBT) ± external beam radiotherapy (EBRT) in postoperative endometrial cancer (PEC).MethodsOne hundred and twenty-six PEC patients treated with VBT ± EBRT were retrospectively analysed considering age, body mass index, applicator diameter, clinical target volume (CTV), use of dilators, chemotherapy and EQD2(α/β=3)at the most exposed 2 cm3of the CTV as prognostic factors for vaginal complications. Late vaginal complications were evaluated using objective LENT-SOMA criteria. Statistics: descriptive analysis, Chi-square, Fisher and Student tests were applied. Univariate and multivariate analyses were performed with the Baptista–Pike exact method and multiple logistic regression.ResultsMean age was 65 years (SD ± 10), and median follow-up was 66 months (8–104). 19/126 patients (15%) showed G2-late vaginal complications, and 107/126 (85%) G0–G1. Univariate analysis showed: CTV ≤ 9 cm3(p= 0.036), use of dilators < 9 months (p= 0.015), and total ≥ 68 Gy EQD2 received by 2 cm3of CTV (p= 0.039) were associated with G2-late vaginal toxicity. Multivariate analysis showed the use of dilators < 9 months as an independent prognostic factor for G2-late vaginal toxicity (p= 0.043, OR 8.59, CI 1.59–159.9).ConclusionThe use of dilators < 9 months in VBT ± EBRT for PEC was an independent prognostic factor for G2-late vaginal toxicity. The use of vaginal dilators ≥ 9 months requires further analysis in studies evaluating late vaginal toxicity.