Abstract: A method and apparatus for sterilization of a dialysis system. The dialysis system comprises a dialyzer, a receptacle for water and a receptacle for dialysis concentrate, and fluid conducting means for conducting fluids from the receptacles for water and dialysis concentrate to and through the dialyzer. The method includes the steps of terminating the conducting of dialysis concentrate through the fluid conducting means, introducing sterilizing agent into the fluid conducting means at a first point in the fluid conducting means, conducting the sterilizing agent through the fluid conducting means downstream of the first point, and directing a portion of the sterilizing agent from a second point in the fluid conducting means to a third point in the fluid conducting means, the second point being downstream of the first point and the third point being upstream of the first point.