Background: Elderly people and patients with colorectal cancer (CRC) are both at high risk of malnutrition. Therefore, it is of great significance to explore suitable malnutrition screening and diagnostic indicators for elderly patients with CRC. Recently, the Global Leadership Initiative on Malnutrition (GLIM) proposed new diagnostic criteria for malnutrition. The aim of this article was to evaluate the diagnostic value of GLIM criteria for malnutrition in elderly colorectal patients. We explored the relationship between GLIM-malnutrition, post-operative complications and the long-term prognosis of elderly colorectal patients., Methods: Elderly patients (aged ≥65 years) who underwent CRC surgery from January 2015 to December 2018 were included. Malnutrition was diagnosed based on the GLIM criteria. The relationships between GLIM-malnutrition and clinical characteristics were analyzed by t -tests, Mann-Whitney U tests, and chi-squared tests. The relationships between GLIM-malnutrition and post-operative complications were analyzed by chi-squared tests, and logistic regression analyses. The relationships between GLIM-malnutrition and the long-term prognosis were analyzed by Kaplan-Meier analyses and logistic and Cox regression analyses., Results: A total of 385 elderly patients were included in this study, and 118 patients (30.65%) were diagnosed with malnutrition according to the GLIM criteria. GLIM-malnutrition was significantly associated with older age, lower body mass index (BMI), lower grip strength, tumor location, higher Nutrition Risk Screening 2002 (NRS-2002), and lower levels of albumin and hemoglobin. GLIM-malnutrition was an independent risk factor [odds ratio (OR): 1.753, 95% confidence interval (CI): 1.100-2.795, P=0.018] for post-operative complications. Cox regression analysis showed that GLIM-malnutrition was an independent risk factor for overall survival in elderly patients with CRC., Conclusions: The GLIM criteria are feasible diagnostic criteria for malnutrition of elderly patients with CRC. GLIM-malnutrition is significantly associated with post-operative complications and overall survival in elderly patients with CRC., Competing Interests: Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://jgo.amegroups.com/article/view/10.21037/jgo-23-543/coif). The authors have no conflicts of interest to declare., (2023 Journal of Gastrointestinal Oncology. All rights reserved.)