Abstract: A device for equalizing a patient's potential with respect to medical equipment, in particular upon recording an electrocardiogram, includes at least two measuring electrodes and a reference electrode which are adapted to be applied to the patient, a drive-signal generation circuit having its output side connected to said reference electrode, a control circuit which has supplied thereto the measuring signals from said measuring electrodes and which examines whether the measuring signals lie within a predetermined range, said control circuit supplying said measuring signals to inputs of the drive-signal generation circuit, if said measuring signals lie within a predetermined range.