Abstract: Body cell mass index (BCMI) is one of the important parameters of bioelectrical impedance measurement, BCMI has never been affected by maintenance hemodialysis (MHD) hydration status. It is sensitive to changes of muscle mass, protein organization, and the presence of micro-inflammatory states, which has been initially applied in clinical practice, including the assessment of nutritional status, micro-inflammatory state, cognitive function, and the prediction of adverse outcomes in MHD patients. This article reviewed the current research progress of BCMI measured by bioelectrical impedance in MHD, in order to guide the clinical management of MHD patients.