This study examined peacekeeping as a risk factor for suicide. In a case-control design, 66 suicides in the Canadian military between 1990-1995 were retrospectively compared with 2601 controls randomly selected from an electronic military database & 66 matched controls with complete personnel & medical data. The authors did not find an increased risk of suicide in peacekeepers except among a subgroup of air force personnel. Here confounding individual factors, isolation from supports & possibly inadequate preparation for deployment, elucidated their suicides. Theatre of deployment did not affect the suicide rate. Military suicides experienced psychosocial stresses & psychiatric illness more often than the matched controls. It is concluded that peacekeeping in itself does not increase overall suicide risk. Careful selection & preparatory military training that encourages intragroup bonding & mutual support may protect against suicide risk. (33 refs.)