We carried out a brief longitudinal mental health screen of 254 members of the UK's Air Assault Brigade before and after deployment to Iraq last year. Analysis of General Health Questionnaire (GHQ–28) scores before and after deployment revealed a lower score after deployment (mean difference=0. 93, 95% CI 0. 35–1. 52). This indicated a highly significant relative improvement in mental health (P < 0. 005). Moreover, only 9 of a larger sample of 421 (2%) exceeded cut-off criteria on the Trauma Screening Questionnaire. These findings suggest that war is not necessarily bad for psychological health.