The symptoms and signs of perilymphatic fistulae (PLF) are very varied and frequently misleading. The operative demonstration of a perilymph leak is not always obvious and the therapeutic results are sometimes disappointing. The study of 26 cases demonstrates certain concepts concerning the diagnostic and therapeutic difficulties. Any atypical cochleovestibular symptoms, particularly occurring in a traumatic context, should suggest the possibility of PLF. Exploratory surgery must be performed according to a rigorous protocol in order to demonstrate the fistula. Search for a fenestra ovalis sign due to pressure on the membrane of the fenestra rotunda may help to reveal a lesion of the annular ligament. Simple filling of the breach is not always effective, especially at the level of the stapes. Stapedectomy frequently constitutes the best solution for fistulae of the fenestra ovalis.