Abstract Background Blood transfusions have been associated with decreased long-term survival in cancer patients, possibly due to immunological factors. This cohort study aimed to investigate associations, if any, between perioperative transfusions and survival in gastroesophageal cancer patients. Methods A population-based cohort study was conducted based on the National Registry for Esophageal and Gastric cancer (NREV), which harbors clinical data including given transfusions. All patients resected for esophageal or gastric cancer in Sweden, between 2017 and 2022, were included and their survival was acquired from the Swedish Cause of Death Registry. Multivariable Cox regression was used to calculate hazard ratios (HR) with 95% confidence intervals (CI), adjusted for confounders (age, American Society of Anesthesiologist class, access of surgery and pathological TNM stage) Results Of 1,368 patients, 227 patients (17%) received perioperative transfusions. Transfusion was associated with an increased risk of all-cause mortality within 3 years of surgery (HR 1.48 95% CI 1.17-1.91). Kaplan-Meier curves depicted worse crude survival in patients having received peroperative transfusion (Figure 1). To exclude the effects of surgery-related postoperative complications on short-term mortality, a sensitivity analysis was performed, excluding patients who died within 30 days of resection, and found that the impact of transfusions on survival remained. Conclusion Perioperative blood transfusions might have a negative impact on survival in patients who undergo gastroesophageal cancer surgery.