The skull clamp system with pressure limiting and alarm systems includes at least one and preferably multiple inwardly power driven immobilizing pins adjustably engaging the skull of a patient. The pin power drive systems includes at least one sensor capable of sensing the degree of back pressure on the pin from contact of the pin against the bone of the patient, the sensor being capable of signaling the drive system to stop when the sensor detects a preselected degree of back pressure. The sensor is also capable of signaling an alarm to warn of any reduction of pressure applied to the pins that might result from pin slippage.