The ratio of the volumes of extracellular water to total body water (ECW/TBW) obtained by multi-frequency bioelectrical impedance analysis (MF-BIA) indicates body water balance. However, the characteristics of ECW/TBW in hemodialysis (HD) patients have not been fully investigated yet. We evaluated correlations of ECW/TBW with body composition, circulatory and body fluid status, and nutritional status in 60 stable maintenance HD patients using MF-BIA. ECW/TBW increased with increasing age and showed significant positive correlations with volume index (VI), cardiothoracic ratio, and brain natriuretic peptide, all of which are indices of circulatory and body fluid status. Furthermore, there were significant negative correlations between ECW/TBW and serum albumin (Alb), the geriatric nutritional risk index, and the normalized protein catabolic rate, all of which indicate nutritional status. Following multiple regression analysis, the independently related factors for total subjects were age, VI, and Alb. In obese HD patients, ECW/TBW tended to decrease, indicating intravascular dehydration. In conclusion, ECW/TBW in HD patients was shown to increase with age and can reflect circulatory, body fluid, and nutritional status, as well as the difference between predetermined dry weight and "optimal body weight" which may change along with a patient's nutritional status. Keywords aging, circulatory and body fluid status, hemodialysis (HD), multi-frequency bioelectrical impedance analysis (MF-BIA), nutritional status, ratio of extracellular water to total body water volume (ECW/TBW)