An apparatus for extracorporeal blood treatment comprises a sensor (10) for emitting a signal indicating a variation in blood volume of an individual (7) subjected to extracorporeal blood treatment and a sensor (14) for emitting a signal indicating a weight loss of the individual. A control unit (20) receives the signals, compares the relation between the relative variation of blood volume (ΔBV%) and the relative variation of weight loss (ΔWL%) of the individual with a desired value, and controls the weight loss of the individual on the basis of the comparison. The apparatus enables automatically controlling a dialysis, preventing some complications due to hypotension.
