An ECG recorder apparatus includes a recorder and a lead arrangement comprising a pair of manually operable resiliently biased jaws carrying electrodes. The electrodes are connected via a connection and a lead to a jack plug which on insertion in the corresponding socket in the recorder causes the recorder to commence operation. The apparatus may be applied by a patient to record an ECG when symptoms are perceived. The electrode arrangement may be easily and reliably applied and the fact that the recorder begins operating automatically reduces the possibility of patient error.