An intracranial pressure (ICP) monitoring system has been developed, consisting of an epidural sensor acting as a pneumatic flow switch connected by tubing to a pneumatic system and microprocessor-based monitoring unit. The frequency response to the system is 8 Hz at 10 mmHg measured peak to peak. ICP and arterial pressure data are collected and maintained in memory. The ICP in memory can be scrolled across a 2-hour or 24-mm graphic and digital video display. When memory is not being recalled, the previous 2 hours or 24 mm of data are displayed on the screen in graphic form. High and low ICP, low cerebral perfusion pressure, and abnormal pressure waves trigger alarms. Calibration of the system is maintained automatically by periodic rezeroing of all transducers to air. Changes in volume within the pneumatic system indicate a leak, and airflow ceases. The software management and alarm systems, as well as available memory, represent the latest in computerized technology.