Objectives In 2003, it was reported that motor neurone disease was linked to military service in the 1990–1991 Gulf War. A large study in the US confirmed an association with military service but found no association with specific conflicts or length of service. Non-veteran studies have suggested an association with physical activity, smoking and other risk factors. We used data from the Scottish Veterans Health Study to investigate the association between motor neurone disease and military service in UK veterans.

Methods Retrospective cohort study of 57 000 veterans born 1945–1985, and 173 000 demographically matched civilians, using Cox proportional hazard models to compare the risk of motor neurone disease overall, and by sex, birth cohort, length of service and year of recruitment. We had no data on smoking prevalence.

Results Veterans had an increased risk of motor neurone disease compared with non-veterans (adjusted HR 1.49, 95% CI 1.01 to 2.21, p=0.046). The increase was independent of birth cohort, length or period of service, or year of recruitment. Risk was associated with a history of trauma or road traffic accident in veterans and non-veterans.

Conclusions We confirmed an increased risk of motor neurone disease in military veterans, although the absolute risk is extremely low. We found no evidence that the increased risk was associated with any specific conflict. We could not rule out that smoking (and perhaps other lifestyle factors) may be responsible for our findings. Trauma may play a role in the increased risk but further studies are needed.