Background/Aims: We aimed to assess the validity of the Korean translated version of the Clinical Frailty Scale (CFS) in determining the frailty status in geriatric outpatients.Methods: The records of 123 ambulatory outpatients who had undergone CFS and comprehensive geriatric assessments (CGAs) including measurements for the Cardiovascular Health Study (CHS) frailty scale and the frailty index (CGA-FI) were analyzed. Correlations between CFS, CHS frailty scale, and CGA-FI were assessed. The ability of CFS to classify frailty status was calculated using the CHS frailty scale and CGA-FI as references.Results: The mean CFS score was 3.2 in the study population, with a mean age of 77.49 years (45.5% men). Individuals with higher CFS scores were older, had a greater burden of chronic diseases, and worse daily functions and cognitive performance. CFS scores positively correlated with CGA-FI (B = 0.78, p < 0.001) and CHS frailty scale (B = 0.67, p < 0.001) scores. For CFS, C-statistics to classify frailty by CGA-FI and CHS scale were 0.905 and 0.826, respectively. The cut-off value of CFS ≥ 4 maximized Youden’s J to classify frailty by both the CHS scale and CGAFI.Conclusions: The CFS is a valid screening tool to assess the frailty status in outpatients of a geriatric clinic in Korea. As a simple and quick measure, the CFS may facilitate frailty assessments in real-world clinical practice.