The benefit of using gelatin solution in cardiac surgery is still controversial. Previous data suggested adverse interactions of gelatin infusion with acute kidney injury (AKI) or coagulopathy. The purpose of this study was to evaluate the association between perioperative gelatin use and fluid overload (FO), hemodynamic stability, and outcomes compared to crystalloid-based fluid management. A retrospective study design. At a single-center tertiary university setting. Propensity score-matched cohort study of 191 pairs of patients scheduled for cardiac surgery. Patients received either gelatin+crystalloid or pure crystalloid-based perioperative fluid management. The primary outcomes were the frequency of FO and hemodynamic stability defined by the vasoactive-inotropic score. Postoperative complications and 3-year survival were analyzed also. Patients who received gelatin experienced more frequent postoperative FO than controls (11.0% v 3.1%, p=0.006) despite comparable hemodynamic stability in both groups. Gelatin administration was linked with a higher rate of postoperative complications, including blood loss, AKI, and new-onset postoperative atrial fibrillation. Use of gelatin infusion resulted in an adjusted odds ratio of 1.982 (95% CI 1.051-3.736, p=0.035) for developing early postoperative AKI. This study confirmed a dose-dependent relationship between gelatin infusion and AKI. Thirty-day mortality and 3-year survival were similar in the groups. Gelatin administration versus crystalloid fluid management showed a significant association with a higher rate of FO and an increased risk for early postoperative AKI in a dose-dependent manner.