Background: Frailty is one of the most relevant clinical expressions of ageing and a powerful indicator of the health status of older populations. Tools to identify frailty can be classified into three groups based on rules (the Tilburg Frailty Indicator (TFI)), functional performance (Gait Speed (GS) and Timed Up and Go (TUG) tests), and biomarkers (e.g., SOX2 expression). This study explores the concordance between two functional tests (GS and TUG), blood SOX2 levels and TFI scores in assessing frailty.