A method for emptying a blood circuit of an apparatus for the extracorporeal treatment of blood after interrupting a treatment session. The apparatus has a blood treatment device with first and second compartments separated by a semi permeable membrane, an arterial pipe connected to an inlet of the first compartment, a venous pipe connected to an outlet of the first compartment and a second end, and a used liquid circuit having a drain pipe connected to an outlet of the second compartment. The method involves the closing of the blood circuit on itself. The blood circuit includes the arterial pipe, the first compartment of the blood treatment apparatus, and the venous pipe, in order to form a closed loop circuit after the arterial and venous pipes have been disconnected from the vascular system of the patient. The blood circuit contains a liquid, which is transferred from the closed loop circuit into the used liquid circuit. The liquid transferred into the used liquid circuit is then drained using the drain pipe.