Abstract: There is disclosed an ECG monitoring device for attachment to the skin of an individual, which device includes a plurality of electrodes for monitoring bio-skin potential disposed at suitable locations on a base or substrate. The device includes a first resilient sponge-like sheet, and a second resilient sponge-like sheet adhesively attached to the first sheet and having a plurality of openings formed therein. A number of electrodes are attached to the second sheet by an adhesive coating, with the connector elements of the respective electrodes in place in the openings and secured to lead wires for attachment to monitoring apparatus. The individual electrodes include an adhesive base surface that can be exposed upon removal of a cover structure which normally overlies a pre-gelled pad and said base surface. The adhesively coated base surfaces of the electrodes are used to affix the device to the patient.