Background: Stage is a critical determinant of treatment among endometrial carcinoma patients; understanding patterns of tumor spread may suggest approaches to improve staging. Specifically, the importance of exfoliation of endometrial carcinoma cells through the fallopian tubes into the peritoneum is ill defined. We assessed the hypothesis that tubal ligation (TL), which should impede transtubal passage of cells, is associated with lower endometrial carcinoma stage at presentation and, consequently, lower mortality. Methods: The NRG Oncology/Gynecologic Oncology Group (GOG) 210 Trial included 4489 endometrial carcinoma patients who completed a risk factor questionnaire that included TL history. Pathology data were derived from clinical reports and central review. We used logistic regression to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for associations between TL with stage and peritoneal metastasis, overall and by tumor subtype. Cox regression was used to estimate hazard ratios (HRs) and 95% confidence intervals for TL and mortality. All statistical tests were two-sided. Results: Compared with stage I, TL was inversely associated with stage III (OR = 0.63, 95% CI = 0.52 to 0.78) and stage IV carcinomas (OR = 0.14, 95% CI = 0.08 to 0.24) overall and among individual tumor subtypes. TL was inversely related to peritoneal metastasis overall (OR = 0.39, 95% CI = 0.22 to 0.68) and among serous carcinomas (OR = 0.28, 95% CI = 0.11 to 0.68). In multivariable models unadjusted for stage, TL was associated with lower endometrial carcinoma-specific mortality (HR = 0.74, 95% CI = 0.61 to 0.91); however, adjustment for stage eliminated the survival advantage. Similar relationships with all-cause mortality were observed. Conclusions: TL is associated with lower stage and mortality among women with aggressive endometrial carcinomas, suggesting transtubal spread is clinically important. Future studies should evaluate whether detection of intraluminal tumor cells is prognostically relevant.