INTRODUCTION: Insurance status may impact survival of patients undergoing surgery for solid tumor malignancies. In this study we examine whether quality of cancer care is impacted by primary payer for patients undergoing surgery for gastrointestinal (GI) cancer. Methods: This is a retrospective cohort study of 522,692 patients in the National Cancer Database diagnosed between 2004 and 2017 who underwent surgical resection of a GI cancer. The primary endpoints were negative resection margins, adequate lymphadenectomies as per National Comprehensive Cancer Network guidelines and use of adjuvant therapy. Multivariable logistic regressions were fit to determine differences in quality of care by insurance and when controlling for covariates (sex, age, race, ethnicity, income quartile, facility type, primary cancer site, clinical stage, grade and comorbidity score). Results: After adjustment for covariates and when compared with Medicare, Medicaid (OR 0.88 (95%CI 0.85-0.92); P<.001) and uninsured patients (0.80 (0.76-0.84); P<.001) were less likely to have negative surgical margins overall, and in colectomies, proctectomies and proctocolectomies. Patients with private insurance, however, were more likely to have negative resections than those with Medicare (1.06 (1.03-1.08); P<.001) overall, and in esophagectomies, pancreatectomies and proctectomies. Similarly, Medicaid (0.95 (0.92-0.98); P=.003) and uninsured patients (0.90 (0.86-0.94); P<.001) were less likely to have adequate lymphadenectomies overall, and for esophagectomies and proctectomies. Patients with private insurance were more likely to have adequate lymphadenectomies than those with Medicare (1.04 (1.02-1.06); P<.001), including for proctectomies and gastrectomies. Adjuvant systemic therapy was used more frequently in private insurance (1.17 (1.15-1.19); P<.001) and Medicaid (1.05 (1.02-1.09); P=.005) patients compared to those in Medicare. Adjuvant therapy for colectomies, esophagectomies, hepatectomies, pancreatectomies, proctectomies, proctocolectomies, gastrectomies and biliary resections was more common in private insurance vs Medicare. Conclusion: Uninsured and Medicaid patients receive inferior quality of GI surgical oncology care compared to those with Medicare or private insurance and insurance status influences administration of adjuvant therapy. Additional research is needed to probe why insurance affects quality of care and whether hospital or physician bias may be driving these inequities.