Abstract: A process and device for noninvasive measurement of cerebral blood flow simultaneously determines of a blood flow index which is directly proportional to the blood flow. Cerebral surge kinetics of an intravenously injected indicator dye with absorption properties in the near-infrared spectrum is sensed by near-infrared spectroscopy and the arterial surge kinetics is sensed by pulse densitometry. A device for carrying out this process consists of a multichannel apparatus having at least two near-infrared spectroscopes, each having two pulsed monochromatic light sources, a measuring and a reference wavelength, in the range of the near-infrared spectrum; one or more light sensors connected to a photomultiplier; and a noninvasive measuring device which determines, by pulse densitometry, the concentration of the tracer in the arterial blood of the circulatory system.