Abstract: Background: Little is known aboutthe psychological health or treatment psychological health or treatment experiences of those who haveleft the British armed forces. Aims: To describe the frequency and associations of common mental disorders associations of common mental disorders and help-seeking behaviours in a representative sample of UK veterans at high risk of mental health problems. Method: A cross-sectional telephone survey of 496 ‘vulnerable’ex-service personnel selected from an existing epidemiological military cohort. Results: The response rate was 64%; 44% of these had a psychiatric diagnosis, most commonly depression. Those with a diagnosis were more likely to be of lower rank and divorced or separated. Just over half of those with self-reported mental health problems were currently seeking help, most from their general practitioners. Most help-seekers received treatment, usually medication; 28% were in touch with a service charity and 4% were receiving cognitive behavioural therapy. Conclusions: Depression is more common than post-traumatic stress disorder in UK ex-service personnel. Only about half of those who have a diagnosis are seeking help currently, and few see specialists.