An electrosurgical instrument includes a handpiece, an electrode assembly comprising one or more electrodes attached to the handpiece, and connection means for connecting the handpiece to an electrosurgical generator. The handpiece comprises a housing, fluid supply lines for directing a cooling fluid to and from the electrode assembly, and a pump for driving cooling fluid through the fluid supply lines. The handpiece may also include a fluid reservoir. The pump, the fluid supply lines, and the reservoir are all wholly contained within the housing.