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Unilateral vestibular lesion results in postural balance deficits, which progressively vanish with time compensation. This functional recovery is caused due to the reorganization of the CNS structures and afferent inputs, mainly of the proprioceptive afferentation. Our aim was to determine the postural effect of leg proprioceptive input induced by the Achilles tendon (AT) vibration in standing patients with unilateral vestibular hypofunction. The examined patients (9 patients unilateral vestibular neuritis and 3 patients with Meniere's disease) had unilaterally decreased caloric responses. The control were 20 healthy volunteers with intact vestibular and motor functions. The postural responses evoked by AT vibration were evaluated by the symmetry of centre of pressure (COP) of the subject. The postural responses induced by the AT vibration in the healthy were bilaterally symmetrical. In the patients the body lean evoked by vibration on the side of intact vestibular apparatus was significantly decreased. The AT vibration on the lesioned side evoked practically identical response to the response of healthy subjects. In the repeated examination after 6 months the asymmetry disappeared which was in accordance with the recovered clinical state. The findings of asymmetry of postural COP displacement in patients with acute unilateral vestibular hypofunction documented transitory asymmetry of influence from leg proprioceptive inputs. The direction of decreased postural response to the proprioceptive stimuli was the same as pathological body lean of patient to the side of lesioned vestibular apparatus. This fact allows us to hypothesize that the postural responses evoked by leg proprioceptive inputs, directionally identical with the pathological body lean induced by asymmetry of vestibular afferentation are inhibited. (Fig. 3, Ref. 15.)