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 array preferably includes an adhesion layer to help keep the electrode microstructures inserted into the epidermis during the duration of the therapeutic treatment, and temperature and condition monitoring devices to ensure proper treatment and enhance patient safety.