['To evaluate the prognostic performance of tumour-free distance (TFD) compared with depth of invasion (DOI) and percentage of myometrial invasion (MI).', 'Retrospective cohort study.', 'Regional gynaecological oncology centre.', 'All women identified with stage I-III endometrioid endometrial carcinoma from January 2000 to December 2007, who had surgery at the Northern Gynaecological Oncology Centre (NGOC).', 'Surgicopathological, follow-up and survival data were collected. Univariate and multivariate analyses were performed comparing TFD, DOI and MI with known prognostic factors. The prognostic accuracy of TFD was assessed by receiver operating characteristic (ROC) curve analyses, and an optimum cut-off was proposed.', 'Death from disease, recurrence and pelvic lymph node involvement.', 'A total of 288 women were identified. The median follow-up time was 67 months, with 40 recurrences and 32 disease-related deaths. When TFD, DOI and MI were separately examined in multivariate analyses with other covariates, TFD was an independent predictor of death from disease (HR 1.22; 95% CI 1.00-1.48; P = 0.05). In multivariate analyses including all three measures together (TFD, DOI and MI), TFD was an independent predictor of death from disease (HR 1.49; 95% CI 1.03-2.16; P = 0.04) and recurrence (HR 1.39; 95% CI 1.01-1.91; P = 0.05). TFD was also an independent predictor of lymph node involvement when examined separately (OR 0.74; 95% CI 0.56-0.96; P = 0.03), and together with DOI and MI (OR 0.67; 95% CI 0.49-0.92; P = 0.01), in women who had pelvic lymphadenectomy (n = 86). A TFD cut-off of 1.75 mm showed good prognostic performance.'] Is tumour-free distance from serosa a better prognostic indicator than depth of invasion and percentage myometrial invasion in endometrioid endometrial cancer?