This book highlights recent advances in our understanding of sarcopenia and frailty in CKD. The prevalence of sarcopenia and frailty increases substantially as CKD progresses, and experimental studies have demonstrated the pivotal role of accumulated uremic toxin in the development of muscle wasting. Further, sarcopenia and frailty are associated with falls, bone fractures, cognitive impairment, and poor survival prognoses, especially in elderly CKD patients. The syndromes are also related to the risk of end-stage kidney disease.