Head trauma with it's increasing rate is one of the most common causes of neurological disorders in this modern technological age. Remarkably, little is known about the development of aduitory and vestibular disturbances due to head injuries and less is known about the incidence and nature of otoneurological disorders following trauma despite their relative importance both medically and legally. Head injuries are known to cause auditory and vestibular lesions. According to the literature, the incidence of hearing defects varies. It is readily understandable when it is considered that the nature of the patients dealt with varies considerably with different authors. However, many investigators have encountered auditory and vestibular lesions in about a half of the patients sustaining head injuries. A high incidence of vestibular lesion has been reported and often, it is even higher than the hearing damage. The object of the present investigation is to establish the incidence and nature of hearing and vestibular defects on the basis of an otoneurological study in the immediate postinjury period in patients with head injuries, to try to determine whether there is any risk factors necessiating a more comprehensive assessment of audiovestibular function and to clarify their reversibility during a 3-month follow up period. The material consisted of 117 patients with head injuries who visited the department of ENT, N-S and E-R between Sep. 1981 and Feb. 1982. According to the results of this investigation, the following conclusions can be drawn. 1) The audiologic examinations revealed that 58.1%(68 pts/117 pts) had impaired hearing at the initial examination. 51 patients were examined at 3 months and the incidence of residual hearing loss was 45.1%(23 pts/51 pts). Among the sensorineural types, group A showed favorable prognosis, but group B and C seemed far less favorable. 2) The incidence of vertigo caused by head injuries was 75.2%(88 pts/117 pts) at the initial examination. At 3 months, 51 patients were examined and the incidence dropped to 23.5%(12 pts/51 pts). 3) The incidence of tinnitus was 27.4%(32 pts/117 pts). At 3 months examination, the incidence dropped to 11.8%(6 pts/51 pts). 4) A trauma to the temporal region was more likely to cause vertigo and gaze nystagmus than to any other region. 5) The incidence of hearing loss and vertigo was significantly higher in the patients with presence of unconsciousness period than those with absence of unconsciousness period. 6) At 3 months examination, the prognosis turned out to be less favorable in the patients with hearing loss or vertigo which seemed to be of central origin than those with hearing loss or vertigo originating from the peripheral.