Background. Peace-keeping duties are associated with unique stresses for military personnel. There have been few reports on the effects of peace-keeping on psychological health. Method. We used data from a cross-sectional study originally established to examine health effects of service in the Gulf War, which included a control group who had been deployed in Bosnia (N=2049). This group was examined to establish which demographic, occupational, and deployment-related risk factors were associated with psychological distress measured on the General Health Questionnaire (GHQ-12) and stress symptoms akin to a post-traumatic stress reactions. Results. The main risk factors for stress symptoms in the Bosnia group were - lower rank, being deployed early in the campaign, having more deployment-related exposures, and serving on staff duties. There was no protective effect of previous deployments to the Falklands or Northern Ireland, and time off following deployment was not protective. For GHQ-12 cases, the main risk factors were female gender, lower rank, increased deployment-related exposures and serving on staff duties. Conclusions. This study suggests that stress symptoms and GHQ-12 cases, are strongly predicted both by experiences during deployment and demographic factors.