Introduction: Frailty is a geriatric syndrome conferring a high risk of declining functional capacities. Some serum biomarkers were associated with frailty, but no study has investigated this possible association among community-dwelling seniors with minor injuries in the emergency department (ED). The aim was to determine if ED serum biomarker assay combined with frailty status improve the prediction of 3-months functional or mobility impairments in this population, beyond frailty status alone. Methods: This prospective sub-study of the CETI cohort includes 190 participants (age 65 years, ED consultation within 2 weeks of a minor injury, independent in daily activities 4 weeks prior to injury, and discharged home from EDs). Biomarkers were obtained from blood samples at baseline (ED visit). Normal vs. at risk physiological states were defined according to clinical threshold values. Also, the patients were screened for frailty at baseline) while their functional (OARS scale) and mobility characteristics were assessed at the ED visit and 3 months later. Patients were classified as robust or pre-frail/frail according of the CHSA-CFS and SOF scales. Simple generalized linear models with a binomial distribution and a log link function were used to explore the differences in functional and mobility outcomes at three months across sub-groups (RR). Results: When compared to robust ones, ED pre-frail/frail patients were less functional in their instrumental activities of day living (p=0.004), slower walkers (p=0.02), more frequent users of walking aids (p=0.03), more fearful of falling (p=0.006), went outside their home less often weekly (p=0.004) and had higher abnormal creatinine levels (p=0.02). We observed an overall 3-month functional decline in around 10% of patients combined with worsened mobility characteristics. We found that vitamin D [RR: 0.51 (0.07-3.9)], glucose (RR: 0.27 [(0.03-2.16)]) and creatinine (RR: [1.10 [(0.40-2.97]) modulate the prediction of 3-months mobility impairments. However, ED frailty status with CHSA-CFS and SOF scales clearly remained the stronger predictor of mobility impairments [vitamin DRR: 2.93 (1.12-7.65); glucoseRR: 2.36 (0.85-6.55); creatinine: RR2.06 (1.21-3.53)]. Conclusion: Since they do not improve the prediction of 3-months functional or mobility impairments associated with frailty status, ED biomarker assays are not useful in adequately screening for frailty among independent seniors with minor injuries.