We present a recurrent syncope case with no clear origin or not stabilized after complete diagnostic exploration including echocardiogram, Holter, carotid Doppler, electrophysiologic study, computerized tomography, etc. Due to its recurrence and sudden appearance which was presumed to be of cardiac origin we implanted a long recording subcutaneous Holter system, the first unit used in Spain. This device, which has several advantages compared to external recorders previous in use, facilitated the patient's diagnosis (arrhythmic syncope of cardiac origin due to a paroxysmal atrioventricular block) one month after implantation. We describe the system, which includes a recorder and an external activator, its handling and diagnostic capabilities as well as the implantation procedures.