Abstract: A hand-held or portable diathermy apparatus is disclosed comprising a housing, a battery power supply preferably within the housing, and at least one electrode carried by the housing. The apparatus includes a radio frequency power generator for generating an oscillatory current ranging between about 1 kilohertz and about 20 megahertz, and supplying this oscillatory current to the electrodes. A manually operated switch is carried by the housing for selective energization of the radio frequency generator whereby, upon energization thereof, the apparatus is capable of being cycled several times outputting up to about 20 watts of power for up to 20 seconds or more on each cycle.