Abstract Introduction The Clinical Frailty Score (CFS) is a reliable predictor of outcomes for older patients in the acute hospital setting and is used to guide management decisions. Our hospital routinely calculates the CFS for older adults on admission to the Emergency Department (ED). Patients admitted under general surgery will then be referred for a Comprehensive Geriatric Assessment (CGA) by our Perioperative Medicine for the Older Patients undergoing Surgery (POPS) team who also calculate CFS. This study aimed to compare the CFS calculated in ED and CGA for these patients. Methods We performed a single centre prospective study of emergency general surgical admissions who were reviewed as an inpatient by our POPS team between August 2022 and September 2023. CFS from ED documentation was compared to that after CGA. A two tailed, paired t test was performed to compare the CFS on admission and after CGA using GraphPad Prism version 10.0. Results A total of 293 patients were identified with a mean age of 79 years(65-102). There was a difference between the admission CFS [4.2 (3.9-4.4 95%CI)] and the CFS following POPS review [4.5 (4.3-4.7 95%CI)] which was statistically significant (p<0.0001). Univariate analysis showed that CFS was predictive of length of hospital stay. Conclusion CFS calculated in the ED can both over and underestimate the degree of frailty when compared to the CFS calculated during the CGA. As evidence suggests that CFS is predictive of outcomes in this cohort, we suggest staff are adequately trained in undertaking an accurate assessment of this score.