Ischemia and hypoxia are frequent potential sources of secondary brain damage after a variety of brain injuries. Cerebral oxygen extraction may be altered by coma as well as therapeutic interventions. In consequence, monitoring of cerebral O2 availability and utilization has become an important challenge for clinicians. However, measurement of cerebral oxygen extraction in children currently is not included into routine clinical care. This paper describes the measurement of O2-saturation in the jugular bulb in four comatose infants and children (in one continuously) following cardiac arrest or head injury. Our data demonstrate that this procedure served as a valuable tool in the management of those patients. Arterio-jugular oxygen content and lactate differences were used for the establishment and adjustment of therapeutic procedures and moreover, provided relevant information for the interpretation of other cerebral surveillance parameters.