Urea Kinetic Modeling (UKM) is recognized as the most efficient method for quantitating hemodialysis treatments: and the dimensionless-parameter Kt/V is widely used to monitor dialysis prescription, Although many shortcut methods have been developed to directly calculate it, there is no agreement an which is the best method to be applied. We present a new UKM model, which corrects the Urea balance carried on by Sargent[1]. The model is checked to the Urea rebound into account, and in this way is used as reference model in a Clinical study.