At 3 to 4 weeks after the December 2004 tsunami disaster we assessed symptoms of posttraumatic stress disorder (PTSD) in 264 children who lived in severely affected coastal communities in Manadkadu (northern coast), Kosgoda (western coast), and Galle (southern coast) in Sri Lanka. The prevalence rate of tsunami-related posttraumatic stress disorder (PTSD) (ignoring the time criterion) ranged between 14% and 39% and an additional 5% to 8% had PTSD unrelated to the tsunami. The PTSD symptoms were explained by the severity of the trauma exposure and family loss, as well as previous traumatic events. The results confirm the relevance of the individual history of traumatic events for the genesis of PTSD and indicate a high need of mental health assistance among the tsunami-affected children in Sri Lanka.