Aging and CKD, especially under dialysis are associated with malnutrition, comorbidity, polypharmacy, anemia, cognitive impairment, and these are risk factors for frailty. A study shows that among patients attending outpatient clinic for advanced CKD, the prevalence of frailty was upto 45% by Fried’s frailty phenotype criteria. The problem is that Frail elderly become vulnerable to surgery, immunotherapy, and acute illness and end up with worse health outcomes and mortality. A 3 year follow-up study on ambulatory, stroke free participants with stage 2-4 CKD found that each 0.1-m/s decrement in gait speed is a/w a 26% higher risk for death and the risk was higher that eGFR, Hb, CRP, albumin. Frailty is defined as significant decline in functional reserve of multiple organ systems, and the resultant extreme vulnerability of the organism to endogenous and exogenous stressors. The most common ways of diagnosing frailty are the phenotypic and deficit accumulation approaches. • 1. Frailty Phenotype The phenotypic approach, or Fried’s frailty phenotype, classifies a person as frail if three or more of the five frailty items are present. The five items are (1) slow walking speed, (2) impaired grip strength, (3) declining physical activity levels, (4) exhaustion, and (5) unintended weight loss. The presence of just one or two of the five items is defined as prefrailty, and none of them indicates healthy or robust. The Fried’s frailty phenotype focuses on physical domains, and so it is sometimes recognized as the physical frailty phenotype. 2. Frailty Index The other approach to defining frailty is the frailty index (FI), which is a sum of health deficits. In FI, health deficits can be from any physical or mental disability, symptom or sign, disease, or laboratory finding. The rationale for counting health deficits in FI is that the more health problems an individual has, the greater their risk of being frail and having adverse health outcomes. The index is expressed as the number of deficits present divided by the total number of deficits considered. For example, if 40 deficits were considered, and 10 were present in a given person, that person’s FI would be 10/40=0.25. Therefore, FI ranges from 0 to 1, and the higher the FI score, the frailer the person is considered to be. The author has been organizing a Korean Frailty and Aging Cohort Study(KFACS) for the past 5 years and the study is going on. Based on the KFACS study, the risk factors of physical frailty were as follows: malnutrition, sarcopenia, severe mobility limitation, poor social capital, rural dwellers, depressive symptoms, poor self- perceived health, polypharmacy, elevated high-sensitivity C-reactive protein, elevated glycosylated hemoglobin, low 25-hydroxy vitamin D level, longer Timed Up and Go, and low Short Physical Performance Battery score.