An endometrial ablation apparatus for selectively destroying an endometrial lining of an organ in a body including an expandable electrode means for extending the organ and effecting electrical contact with the endometrial lining to be destroyed and an external electrode adapted to contact the outer surface of the body； the expandable electrode containing an electrically non-conductive expansion medium and a variable conductive matrix； and a power source or sources connected to the expandable electrode means and to the external electrode, the power source being adapted to provide radio-frequency electric power to the expandable electrode.
