Fluid shifts are commonplace in chronic hemodialysis patients during the intra- and interdialytic periods. In this study, we evaluated fluid shifts of body compartments using both bioimpedance spectroscopy and blood volume monitoring from the start to the end of hemodialysis. 24 stable hemodialysis patients were included on the study. Relative change of blood volume was progressively reduced from the start to the end of hemodialysis (1 hr, -7.22+/-3.23%; 2 hr, -9.78+/-4.69%; 3 hr, -12.88+/-5.65%; 4 hr, -15.41+/-6.54%, respectively). Mean % reduction of intracellular fluid was not significantly different to that of extracellular fluid at the end of hemodialysis (delta ICF, -6.58+/-5.34% vs. delta ECF, -7.07+/-5.12%). Mean % fluid reduction of arms, legs and trunk was -11.98+/-6.76%, -6.43+/-4.37% and -7.47+/-4.56%, respectively at the end of hemodialysis. There were 3 characteristic patterns in blood-volume change. Similar amounts of fluid were removed from the extracellular and intracellular compartments during hemodialysis, with the arms showing the greatest loss in terms of body segments. The pattern of blood volume change measured by blood volume monitoring may be useful for more accurate determination of dry-weight and for correcting volume status in hemodialysis patients.