A method for priming a blood tubing set having a venous line and an arterial line whose connections at the patient side are in communication with two separate inlets of a chamber of, in particular, a bag and whose connections at the machine side are in communication with a dialyzer. The method includes the steps of parallel filling of both the venous and the arterial lines via a feed line so that priming liquid flows through both inlets into the chamber; and circulation of the priming liquid in the circuit of the lines, the dialyzer and the chamber via a pump so that one of the inlets of the chamber acts as an inlet and the other as an outlet.