27Objective: To estimate the frequency of vestibular dysfunction following blunt, blast, and 28 blunt & blast mild traumatic brain injury (mTBI) and thereon assess the long-term impact 29 of vestibular dysfunction on neurobehavioral function and disability independently of co-30 morbid psychiatric symptoms. Setting: Combat Stress residential and Veterans' Outreach 31 drop-in centres for psychological support. Participants: 162 help-seeking UK military 32 veterans. Main measures: Self-reported frequency and severity of mTBI (using the Ohio 33 State Identification Method), Vertigo Symptom Scale, PTSD checklist for DSM5, Kessler 34 Psychological Distress Scale, Neurobehavioral Symptom Inventory, HIT6, Memory 35 Complaints Inventory, WHO Disability Assessment Scale 2.0. Results: 72% of the 36sample reported one or more mTBI over their lifetime. Chi-square analyses indicated that 37 vestibular disturbance, which affected 69% of participants, was equally prevalent 38 following blunt (59%) or blast (47%) injury and most prevalent following blunt and blast 39 combined (83%). Mediation analysis indicated that when PTSD, depression and anxiety 40 were taken into account, vestibular dysfunction in participants with mTBI was directly and 41 independently associated with increased postconcussive symptoms and functional 42 disability. Conclusion: Vestibular dysfunction is common after combined blunt and blast 43 mTBI and singularly predictive of poor long-term mental health. From a treatment 44 perspective, vestibular rehabilitation may provide relief from postconcussive symptoms 45 other than dizziness and imbalance. Keywords: Balance, mTBI, blast, blunt, veterans. 46 47 48 20,950 adults in the US revealed that the 8% who self-reported vestibular vertigo were