Hypervolemia is a major risk factor for hypertension leading to cardiovascular diseases and also a frequent problem in maintenance hemodialysis (MHD) patients. Fluid overload (FO) can be determined by bioimpedance spectroscopy (BIS) which is a new, practical, and non-invasive method. We tried to determine FO by BIS in MHD patients and find out the relationship between FO and clinical features.