This study aimed to determine whether psychological factors associated with Post-Traumatic Stress Disorder (PTSD) identified in Western samples generalize to low Social-Economical-Status (SES) populations in an underdeveloped Asian country. The study included 113 survivors of the 2004-tsunami on the south coast of Sri Lanka, recruited from 4 preschools and 10 villages for displaced persons. With logistic regressions the relations between interview-based PTSD diagnosis and psychological factors were assessed, controlling for putative confounders. Fifteen months post-trauma the prevalence of PTSD was 52.2%. Multivariate analyses indicated that negative interpretation of tsunami-memories was significantly (P <0.005) related to PTSD. Of the putative confounders, gender and (non-replaced) lost work equipment were related to current PTSD (P <0.05). The results indicate that the relation between negative interpretation of trauma memories and PTSD is quite universal, suggesting that interventions focusing on this factor may be important in treatment of tsunami survivors who are suffering from chronic PTSD.