We compared a 12-lead electrocardiogram (ECG) recorded by the patient and transmitted to a cardiology call centre via telephone (tele-ECG) with a standard 12-lead ECG recorded from the same patient at the same time. In 158 patients, tele-ECGs were compared with standard ECGs by two cardiologists and one internist, independently and blindly. In 14 patients peripheral electrodes were displaced, and in 12 patients there were baseline artefacts. These technical errors were corrected by telephone communication in all but two individuals. One patient could not use the tele-ECG device because of disability. Hence, in 155 of 158 patients (98%), the quality of the tele-ECG was adequate for diagnosis. Reliability coefficients (R) for PQ, QRS and QT intervals between tele- and standard ECG were high, with R values of 0.73, 0.75 and 0.79, depending on the physician. Negative T-waves could be detected with very good agreement in the tele-ECG as compared with the standard ECG (kappa values of 0.97, 0.95 and 0.94). The agreement between tele- and standard ECG concerning alterations of the ST segment was very good (kappa = 0.99 for all investigators). Residual signs of myocardial infarction could be detected by tele-ECG, with very good agreement for anterior as well as for posterior localizations (kappa = 0.99 and 1.00). The tele-ECG technique seems a promising approach to reducing pre- and in-hospital time delays to the initiation of thrombolytic therapy.