A case of spontaneous cerebrospinal fluid otorrhea due to a congenital tegmen tympani defect is reported. The etiology and pathogenesis of cerebrospinal fluid otorrhea and of the spontaneous congenital form in particular is discussed, together with the clinical picture and the methods of diagnosis. Reviewing the literature, a middle ear exploration is considered to be the procedure of choice to ascertain the presence and determine the exact locus of the cerebrospinal fluid leak.