A percutaneous electrode array is disclosed for applying therapeutic electrical energy to a treatment site in the body of a patient. The array comprises a plurality of electrode microstructures which are inserted into the epidermis, thereby overcoming the inherent electrical impedance of the outer skin layers and obviating the need to prepare the skin surface prior to an electro-therapy treatment. The portions of the array that will be inserted into the epidermis such as the electrode tips are preferable insulated to eliminate an uncomfortable high electric field that can arise at the edges and tips of the electrode.