A machine for extracorporeal blood treatment comprising a machine-side fluid circuit is disclosed. The machine comprises a heat exchanger for heating cold purification fluid freshly supplied on its intake side, for which purpose used still warm purification fluid flows past its opposite discharge side for a heat exchange, and a circulation valve for changing over between a blood purification mode in which the used purification fluid is disposed of in an open fluid circuit through the discharge side of the heat exchanger into a drain and a disinfection mode in which hot disinfectant is circulated in a closed circuit. The circulation valve is connected downstream of the heat exchanger with respect to the discharge side thereof.
