BACKGROUND: Blood loss resulting in severe anemia is the most common indication for postoperative allogenic red blood cell (RBC) transfusions. In high-income countries, the majority of transfusions is received by elderly patients. Preservatives extend the storage of RBCs, though concerns exist about potential harm from transfusing older RBCs. This study tested the hypothesis that RBC storage duration effects hemoglobin increase in patients older than 70 years who underwent non-cardiac surgery. METHOD: Observations on surgical cohorts from two study sites of the LIBERAL-Trial were collected. Transfusion events and hemoglobin between 2018 and 2022 assessments in addition to manufacturing and product specific quality review information were evaluated. RESULTS: A total of 1626 transfusion events in 505 patients were analyzed. A linear mixed effects model was used to estimate the effect size of different predictors on hemoglobin increment upon red blood cell transfusion. No statistically significant effect of the RBC unit storage duration was found. Confounding variables resulting in higher hemoglobin increase included lower hemoglobin values prior to transfusion, the length of Hb measurement intervals before and after transfusion, as well as the method of RBC cell separation in line with different manufacturer hemoglobin values. CONCLUSIONS: The aspired increase in hemoglobin can be achieved with red blood cell concentrates of any storage duration. In general, elderly patients exhibit a sufficient hemoglobin rise following transfusion. However, if this is associated with improved outcomes cannot be answered.