A hollow coaxial cable adapted for conduction of radio frequency (RF) energy, particularly microwave energy, has a proximal end and a distal end and comprises coaxial inner and outer conductors extending substantially the entire length of the cable from the proximal end to a distal end portion of the cable with a dielectric medium disposed between the inner and outer conductors. The inner conductor comprises an elongated electrically conductive tubular member having a hollow, axially extending lumen, and the outer conductor comprises an elongated electrically conductive tubular member disposed in a substantially coaxial relationship over at least a portion of the inner conductor. An ablating member which delivers radio frequency energy, particularly microwave energy, to body tissue is disposed at a distal end portion of the cable.