A transurethral needle ablation device for the treatment of the prostate of a human male using radio frequency energy wall comprising a sheath having a lumen extending therethrough. A guide tube assembly is slidably mounted in the lumen in the sheath and having a lumen extending therethrough. A needle electrode is slidably mounted in the lumen in the guide tube assembly. An insulating sheath is disposed about the needle electrode so that the distal extremity of the needle electrode is exposed. A handle adapted to be gripped by the human hand is mounted on the proximal extremity of the sheath. Levers are carried by the handle for causing bending of the distal extremity of the guide tube assembly at an angle with respect to its longitudinal axis whereby the lumen in the guide tube assembly can be directed so that it faces the urethral wall. A control is carried by the handle and coupled to the needle electrode and the insulating sleeve for advancing and retracting the needle electrode with respect to the guide tube assembly whereby when the sheath is positioned in the urethra with its distal extremity in the vicinity of the prostate, the needle electrode can be advanced through the urethral wall and into the tissue of the prostate to permit the application of radio frequency energy to the tissue of the prostate surrounding the needle electrode to form a lesion in the prostate.