A method of rinsing and/or filling a blood treatment device, in particular for priming a blood treatment device, is associated with a blood treatment device that includes a membrane filter, in particular a hollow fiber membrane filter, a first partial circuit, and a second partial circuit. The first and the second partial circuits are separated by the membrane filter in a semipermeable manner, with temporarily the first partial circuit being first filled with a fluid with a uniform and/or a pulsatile first volumetric flow rate, with the volumetric flow rate not exceeding a specified threshold value at which the fluid has not completely wetted and/or soaked the membrane. The second partial circuit is temporarily open towards the atmosphere, air is displaced from the first partial circuit into the second partial circuit via the membrane, and during filling no negative pressure is applied to the first partial circuit.