Résumé : Background: The American College of Surgeons (ACS) has developed a Surgical Risk Calculator (SRC) to predict postoperative surgical complications. No studies have reported the performance of the ACS-SRC in oncogeriatric patients. Our objective was to evaluate the predictive performance of the ACS-SRC in these patients, treated with curative surgery for an abdominal malignancy. Methods: This is a retrospective study including 136 patients who underwent elective abdominal oncological surgery, between 2017 and 2019, at our institution. Postoperative complications were classified according to the ACS-SRC, and its predictive performance was analyzed by assessing discrimination and calibration and using receiver operating characteristics and area under the curve (AUC). Results: Discrimination was adequate with AUC of 0.7113 (95% confidence interval [CI]: 1.062–1.202, p = 0.0001; Brier 0.198) for serious complications and 0.7230 (95% CI: 1.101–1.756, p = 0.0057; Brier 0.099) for pneumonia; and poor for sepsis, surgical site infection (SSI), and urinary tract infection (UTI) with AUCs of 0.6636 (95% CI: 1.016–1.353, p = 0.0299; Brier 0.142), 0.6167 (95% CI: 1.003–1.266, p = 0.0450; Brier 0.175), and 0.6598 (95% CI: 1.069–2.145, p = 0.0195; Brier 0.082), respectively. Conclusion: The ACS-SRC is an adequate predictor for serious complications and pneumonia in oncogeriatric patients treated surgically for abdominal cancer. However, the predictive power of the calculator appears to be low for sepsis, UTI, and SSI.