Frailty is a construct originally coined by gerontologists to describe cumulative declines across multiple physiological systems that occur with aging and lead individuals to a state of diminished physiological reserve and increased vulnerability to stressors. Fried et al. provided a standardized definition for frailty, and they created the concept of frailty phenotype which incorporates disturbances across interrelated domains (shrinking, weakness, poor endurance and energy, slowness, and low physical activity level) to indentify old people who are at risk of disability, falls, institutionalization, hospitalization, and premature death. Some authors consider the presence of lean mass reduction (sarcopenia) as part of the frailty phenotype. The frailty status has been documented in 7 % of elderly population and 14 % of not requiring dialysis CKD adult patients. Sarcopenia increases progressively along with loss of renal function in CKD patients and is high in dialysis population. It has been documented that prevalence of frailty in hemodialysis adult patients is around 42 % (35 % in young and 50 % in elderly), having a 2.60-fold higher risk of mortality and 1.43-fold higher number of hospitalization, independent of age, comorbidity, and disability. The Clinical Frailty Scale is the simplest and clinically useful and validated tool for doing a frailty phenotype, while the diagnosis of sarcopenia is based on muscle mass assessment by body imaging techniques, bioimpedance analysis, and muscle strength evaluated with a handheld dynamometer. Frailty treatment can be based on different strategies, such as exercise, nutritional interventions, drugs, vitamins, and antioxidant agents. Finally, palliative care is a very important alternative for very frail and sick patients. In conclusion, since the diagnosis and treatment of frailty and sarcopenia is crucial in geriatrics and all CKD patients, it would be very important to incorporate these evaluations in pre-dialysis, peritoneal dialysis, hemodialysis, and kidney transplant patients in order to detect and consequently treat the frailty phenotype in these groups.