A method for emptying a blood tubing set of a blood treatment device that includes an extracorporeal blood circuit with a membrane filter includes supplying air or gas to the blood tubing set to displace liquid therein. The blood tubing set includes arterial and venous patient blood tubes in communication with a first chamber of the membrane filter. The device also includes a substituate line which opens into the arterial blood tube and/or into the venous blood tube, and a substituate pump. To empty the blood tubing set, the arterial blood tube and the venous blood tube are connected to one another to provide a circuit that includes the membrane filter, the arterial blood tube, and the venous blood tube. The substituate line is disconnected, and the air or gas is pumped into the blood tubing set so as to displace liquid into a second chamber of the membrane filter.