While acting as civilian neuro-psychiatric examiner at an army induction station from November 1940 to November 1943, the author encountered three cases presenting an interesting psychiatric syndrome characterized by hyperesthesias, excessive startle reactions to unexpected stimuli and associated personality reactions which may become incapacitating. Brief clinical studies are included of these three cases which suggest that some individuals showing the excessive startle reaction may become seriously incapacitated by undesirable personality reactions. The person's social difficulties begin when the nature of his disability is discovered and he becomes the victim of incessant and tormenting practical joking. The etiology of the syndrome is unknown but constitutional factors seem important. It is roughly estimated that the syndrome occurs with a frequency of 1 in 2000 among young adult males.It is suggested that the diagnosis of startle neurosis adequately describes this clinical syndrome. It is believed that it may be indicative of central nervous system instability and is a valid cause for rejection for military service.