Abstract: This system for monitoring and assisting isolated persons comprises: a unit (15) decentralized at the desired location for monitoring and assisting the said persons, equipped with a receiver and intended to transmit an alarm signal, in particular by way of the switched telephone network (16), to one or more defined locations (17), in particular a monitoring centre, an emergency centre, neighbours or family; and a portable unit (1) intended to be carried by the said persons, incorporating an emitter which is intended to emit one or more signals in the direction of the decentralized unit (15), the said signals being intended to initiate the transmission of the alarm signal from the decentralized unit in the direction of the said defined locations, and additionally incorporating means (2, 3, 4) for detecting that the person carrying the device has fallen, these means being able to initiate the emission, by the emitter incorporated therein, of the said signals which are intended in turn to initiate the transmissi