Method and device for checking on the delivery performance of at least one first and/or second delivery means of a device for extracorporeal blood treatment by measuring the pressure in a closed container filled at least partially with air by a first pressure measurement, delivering a first liquid volume into the container with the first delivery means, measuring the pressure in the container by a second pressure measurement after delivering the first liquid volume, delivering a second liquid volume out of the container with the second delivery means, measuring the pressure in the container by a third pressure measurement after delivering the second liquid volume out of the container, and evaluating at least the measured values of the first pressure measurement and the third pressure measurement as a criterion for the deviation in the delivery performance.
