A defibrillator (1) comprising electrodes (3), a connection for electrically connecting the electrodes together during a test, a defibrillation signal generator (5), connected to the electrodes, a patient impedance measurement system, connected to the electrodes, comprising a patient signal generator (7) and a patient signal receiver (9), a defibrillator controller (11) connected to the defibrillation signal generator and the patient impedance measurement system, and an electrode test system (13), comprising a control signal device (21), connected to the patient signal receiver, which generates at least one control signal which causes the patient signal receiver to change from a patient signal receive state to an electrode test signal receive state, a test commence signal device (29), connected to the patient signal generator, which generates at least one test commence signal which causes the patient signal generator to send a test signal to the electrodes, and an electrode test signal device (25), connected to the patient signal receiver, which receives an electrode test signal and processes the signal to determine a pass test result or a fail test result for the electrodes. The invention further provides a method of testing electrical conductivity of electrodes of a defibrillator.
