An electrosurgical system includes an electrosurgical instrument and a user alert means (78). The electrosurgical instrument includes an elongate body (1) having a proximal end (2) and a distal end (3), and a pair of jaws (12) carried by the elongate body and disposed at the distal end. An actuator mechanism (5) at the proximal end of the elongate body (1) is movable by the user of the instrument to open and close the jaws (12). The instrument includes first and second electrodes (13), (14) carried by the jaws (12), and at least one strain gauge (75) adapted to provide a signal representative of the closure force applied by the jaws (12). The strain gauge (75) sends signals to the user alert means (78), the user alert means supplying the user of the instrument with an indication (82) of the closure force being applied by the instrument.