An 84-year-old female with profound hearing loss in her left ear since her childhood, complained of vertigo attack with right fluctuating hearing loss and tinnitus. The clinical picture suggested a diagnosis “contralateral delayed endolymphatic hydrops”. On serological test, however, this patient showed moderately positive serology for syphilis. Precise re-inquiry indicated that she was infected with syphilis during pregnancy in her twenties. Thus, we treated this case with isosorbide dehydration, steroids and anti-syphilitic medication. As the result, vertigo attack was suppressed, hearing level became stable, and the rate of syphilitic serology was reduced. It is rare but noteworthy that this case of syphilitic labyrinthitis showed clinical course similar to delayed endolymphatic hydrops. In this paper, we would like to emphasize the necessity of excluding syphilitic labyrinthitis from the differential diagnosis of other vestibular diseases including delayed endolymphatic hydrops.