Introduction This paper presents the burden of mental health cases throughout UK military exercise SAIF SAREEA 3 (SS3), a low-tempo armoured brigade exercise in Oman from June to November 2018, and aims to discuss ways that mental health may be better managed on future large exercises.

Methods A retrospective review of all attendances at army medical facilities and relevant computerised medical records was undertaken.

Results 14 mental health cases were identified, which required 51 follow-up presentations throughout the duration of SS3. This represented 1.2% of all first patient presentations, and 6.3% of all follow-up work. 64% had diagnoses which predated deployment and could all be classified within 10th revision of International Statistical Classification of Diseases and Related Health Problems as either F30–F39 mood (affective) disorders, or F40–F48 neurotic, stress-related and somatoform disorders; all new diagnoses made while deployed were adjustment disorders. The medical officer spent an average of 147 min total clinical care time per patient. Six patients were aeromedically evacuated (AE), which represented 26% of all AE cases from SS3.

Conclusions Presentations were low, but time consuming and with poor disposal outcomes. Most conditions predated the exercise, and could have been predicted to worsen through the deployment. Given the disproportionate burden that mental health cases afforded during SS3, future brigade-sized deployments should include deployed mental health professionals in order to offer evidence-based therapy which should lead to improved disposal outcomes and a reduced AE burden.