Maximal conduction velocity in the supraorbital nerve (afferent fibers for the blink reflex) has been estimated in 12 normal subjects (on the right and left side): the mean value was 41 m/s. Furthermore, this investigation was made on 23 patients with different pathologies (9 with trigeminal neuralgia with hypoesthesia, 8 with multiple sclerosis, 6 with cerebellopontine angle tumor). Normal and pathological results are discussed and diagnostic prospects of this procedure evaluated.