Progress in biomedical engineering has provided implantable and programmable stimulators which allowed application of neurophysiological knowledge to therapeutic attempts on human neurological diseases. Chronic electrodes can be implanted accurately and safely into the brain, against the spinal cord and around the nerves. Therapeutic applications, mainly on pain, dyskinesias and epilepsy are therefore available, which call for careful clinical evaluation, basic and technological research to improve indications and diminish the cost of these methods.