Researches have demonstrated that Posttraumatic stress disorder (PTSD) is one of the most common stress reactions in the face of disasters and significantly associated with a broad range of trauma-induced sequelaes including anxiety, depression, suicidality as well as functional impairments. To date, though many aspects of risk factors with respect to the development and maintenance of PTSD have been addressed, mediating role of dissociation has received relatively less attention. In the present study, we examined relations of PTSD with quality of life, hopelessness, suicidal ideation, and mediational effect of pathological dissociation in these connections. 583 subjects most of whom experienced a severe earthquake participated in the study after two years of the disaster. We found that being female, being single, earthquake exposure, and having greater suicidal ideation were significant predictors of PTSD symptom severity. Role-Physical, Bodily-Pain, General Health and Role-Emotional subscales of the SF-36 were inversely associated with PTSD symptom severity. Pathological dissociation significantly mediated the substantial associations between predictors and PTSD symptom clusters. Chronic dissociation appears to put trauma exposed individuals in jeopardy of prolonged posttraumatic reactions by mediating the negative influences of risk factors in the face of experienced earthquake. (C) 2015 Elsevier Ireland Ltd. All rights reserved.