Background: Modern military operations have incorporated deployed civilians in a variety of roles (e.g. diplomats, private security staff). Many of these roles expose individuals to potentially dangerous or traumatic events. Evidence has shown that such exposures can cause psychological health problems in military personnel. It is likely that the same would be seen among civilians working in such environments. There is however limited research into the health of civilians deployed to war zones. This study compared health outcomes and related behaviours among UK regular and reserve Army personnel with UK civilian personnel deployed in direct support of the UK military in Iraq. Methods: The study sample comprised of 159 Ministry of Defence civilians, 1542 Army regulars and 408 Army reservists, all of whom served in non-combat roles. Data were gathered by questionnaires which asked about deployment experiences, lifestyle factors and health outcomes [i.e. post-traumatic stress disorder (PTSD), general health, multiple physical symptoms and alcohol use]. Results: Fewer deployed UK civilians smoked than regular Army personnel (adjusted OR 0.83 95% CI 0.70-0.98). UK civilians had better overall health and were less likely to report multiple physical symptoms compared with reservists (adjusted ORs 0.64 95% CI 0.44-0.93 and 0.60 95% CI 0.39-0.93, respectively). Conclusions: Overall, the psychological health of deployed civilians appears to be better than that of Army personnel deployed in non-combat roles. Civilians are also less likely to engage in some risky behaviours.