A method and system are provided which are useful for the non-invasive determination and monitoring of cerebral blood oxygenation in a patient. The system comprises a first module for optically generating at least first and second internal jugular venous output signals against time at at least first and second wavelengths of light and a second module for generating first and second cardiac arterial output signals at the first and second wavelengths of light, respectively. The system may additionally include a third module for optically generating at least first and second external jugular venous output signals against time at at least first and second wavelengths of light, and one or more cerebral modules for optically generating at least first and second local cerebral output signals against time at at least first and second wavelengths of light. The system includes a signal processing means adapted to calculate average cerebral, arterial, venous scalp and local cerebral blood oxygenation values based on the output from each of the modules.
