- Patients suffering from severe mental illness (SMI) are considered especially vulnerable to stress. In this study, their use of acute stress services in a military context affecting civilian populations was assessed, using naturally occurring data. The proportion of patients with a previously known SMI, defined as any chronic psychotic disorder or bipolar disorder, among all civilians examined at a center for treatment of stress during a military conflict versus at the ER in usual times, was compared, using the Chi square statistical test. Among 354 subjects examined at the center for treatment of stress, 12 had a SMI diagnosis. Among 404 subjects examined at the ER in usual times, 16 had a SMI diagnosis. Patients with SMI were under-represented, but not in a statistically significant manner, at the center for treatment of stress (χ(2) = 0.31, p = ns). Although these results may imply that patients with SMI are not more vulnerable to external stress than the general population, we believe that they may have difficulties in seeking immediate help in such traumatogenic contexts. In order to reduce the occurrence of PTSD and gain efficacy in the treatment of the primary disorder, psychiatric services should perhaps make a reaching out effort to identify and examine these patients in the community. .