Hearing loss and CT findings of 200 ears from 102 cases with congenital malformation of inner ear were included in our study. Hearing loss was typically bilateral severe, or total deafness. 75 percent of them were found deaf within one-year-old. In addition, 47 patients' (46%) mothers were noted to have caught a cold in first trimester of pregnancy. Temporal bone abnormalties were described as five types: 1. Michel malformation, 2. Mondini malformation, 3. enlargement of the vestibular aqueducts, 4. developmental deformity of cochlear aqueduct, 5. developmental deformity of internal acoustic meatus. Most cases showed malformations of vestibule or vestibular aqueducts.