A medical device for the treatment by radio frequency ablation of a target volume in tissue of a prostate comprising an elongate probe member having proximal and distal extremities and having a passage therein extending from the proximal extremity to the distal extremity. The elongate probe member is sized so that it can be introduced into the urethra. At least one guide tube having proximal and distal extremities is mounted in the passage of the elongate probe member for nonlongitudinal movement therein. The at least one guide tube has a lumen extending therethrough from the proximal extremity to the distal extremity. A radio frequency conductive electrode is disposed in the lumen. A handle is coupled to the proximal extremity of the elongate probe member and includes a finger actuatable mechanism secured to the radio frequency electrode for advancing and retracting the radio frequency electrode with respect to the at least one guide tube. The distal extremity of the at least one guide tube has a curved surface for directing the radio frequency electrode sidewise of the longitudinal axis into the tissue of the prostate.