Children with unilateral total deafness, indistinct in both etiology and time of onset, usually complain of only unilateral hearing loss. Nandate (1963) suggested terming this type of deafness “juvenile unilateral total deafness of unknown etiology”.On the other hand, our clinical experience has indicated that recurrent true vertigo develops preferentially in adolescence or early adulthood in such patients. The objective of this report was to introduce this new clinical aspect of this deafness.1. During the past 14 years, 89 patients with juvenile unilateral total deafness of unknown etiology were seen at the Gunma University Hospital. All patients conformed to the following criteria: i) Unilateral total deafness of unclear etiology and in which the onset of deafness could not be established to be other than very early in infancy; ii) Normal hearing in the other ear or, if deafness were present there also, normal hearing might be inferred to have existed in infancy; iii) Normal tympanic membranes; iv) Absence of central nervous symptoms. Of these patients, recurrent vertigo was the chief complaint of 27, or 30.3%. The age of onset of vertigo ranged from 9 to 60 years. However, in the majority of patients (19 cases: 70.4%), the onset was from 16 to 30 years. The vestibular symptoms were identical to vestibular symptoms seen in Meniere's disease.2. Among these 27 patients with recurrent vertigo of delayed onset, fluctuating sensory-neural auditory disturbances were evident in the originally non-deaf side in 3 (11.1%). These patients were diagnosed as having Meniere's disease.3. In contrast, vertigo attacks in the other 24 patients (88.9%) were never accompanied by cochlear symptoms. Such were considered to fit the delayed hydrops syndrome, a clinical entity newly postulated by Schuknecht (1976) and which is considered to occur as an aftermath of a labyrinthine injury of sufficient magnitude to destroy hearing but leaves the vestibular function intact.