Abstract: A self-locking encephalic electrical probe is used for stereoelectroencephalographic exploration in the treatment of epilepsy or other brain diseases. The probe includes a long, hollow, flexible tube of small diameter, preferably made of medium density polyethylene. A series of at least two electrically conductive rings, preferably made of silver, are located close to one another along the tube for detecting the electrical activity of nerve cells. A series of insulated electrical conductors are located inside the hollow tube, each conductor connecting a conductive ring to a multi-contact terminal located outside the hollow tube. A removable stylet is inserted into the hollow tube to give it rigidity and to control the direction of introduction of the probe into the brain. The stylet is removed from the tube to restore flexibility to the tube after the probe has been introduced in the brain. A self-locking rigid anchor preferably made of stainless steel holds the probe in place.