Three cases of congenital cerebrospinal fluid (CSF) otorrhea from oval window with inner ear dysplasia (Mondini dysplasia) are reported. All three cases had congenital unilateral total deafness with recurrent meningitis. X-ray tomography and high resolution CT of the temporal bone revealed the large vestibule and cystic cochlea. At the operations, all three cases had fistulas on the oval windows and CSF drainages were done in all cases. In the second case a muscular mass was inserted in the cochlea from the enlarged oval window after stapedectomy. In the third case inner ear obliteration with muscle was done after stapedectomy and labyrinthectomy. The fistula was closed and the CSF leakages was controlled in all cases at first operation and they have no recurrence of meningitis.
