Symptoms of dizziness and imbalance are common sequelae following concussion and blast exposures that result in mild traumatic brain injury (mTBI), and these symptoms often last six months or longer. Most studies examining the effect of vestibular dysfunction on postural stability have used symptom scales or tests of vestibulo-ocular reflex (VOR) that measure horizontal semicircular canal (hSCC) function only. Vestibular loss, however, can occur in one or both labyrinths, in one or both branches of the vestibular nerve, and in one or more vestibular sensory end-organs. A prospective case-controlled design was used to determine the effect of mTBI and blast exposure on peripheral vestibular system function, postural stability, and gait. MANOVAs revealed significant differences between the control and mTBI and blast groups for cervical vestibular evoked myogenic potentials, sensory organization test, and dynamic gait index. These findings suggest that mTBI and blast affect the otolith organs, postural stability, and gait. The frequency of test abnormalities ranged from 22 to 71% with the most frequent abnormalities occurring on tests of balance and gait function. Vestibular test abnormalities occurred in 48% of individuals with mTBI and/or blast exposure. Specifically, abnormalities occurred more often in tests of otolith organ function than hSCC function.