The invention relates to a Neuro-navigation system comprising a reflector referencing system including passive reflectors and a marker system with markers or landmarks wherein the reflectors as well as the markers as regards their shape, size and material selection as well as their arrangement or attachment on the parts of the body to be operatively treated and on the surgical instruments are configured so that mapping their locations is substantially facilitated or is able to take place more accurately positioned by a computer/camera unit having a graphic display terminal as well as the operative treatment with the aid of this unit. Optionally a surgical microscope, an ultrasonic diagnostic system as well as a calibration procedure may be integrated in the Neuro-navigation system in accordance with the invention.