Millions of Cambodians suffered profound trauma during the Khmer Rouge era (1975 to 1979). A joint United Nations-Cambodian tribunal (the "Khmer Rouge trials") was empanelled in 2006 to prosecute top Khmer Rouge leaders and began substantive hearings in March 2009. To establish the prevalence of probable posttraumatic stress disorder (PTSD) among adult Cambodians and to assess correlates of PTSD symptoms and disability with perceived justice, desire for revenge, and knowledge of and attitudes toward the trials. A national probability sample of 1017 Cambodians was assembled using a multistage, stratified cluster design, including 813 adults older than 35 years who had been at least 3 years old during the Khmer Rouge era and 204 adults aged 18 to 35 years who had not been exposed to the Khmer Rouge era. Face-to-face interviews were conducted between December 2006 and August 2007. Prevalence of probable PTSD using the PTSD Checklist, Civilian version (cutoff score of 44), and mental and physical disability using the Medical Outcomes Study 12-item Short Form Health Survey. The prevalence of current probable PTSD was 11.2% (95% confidence interval [CI], 8.6%-13.9%) overall and 7.9% (95% CI, 3.8%-12.0%) among the younger group and 14.2% (95% CI, 11.0%-17.3%) in the older group. Probable PTSD was significantly associated with mental disability (40.2% vs 7.9%; adjusted odds ratio [AOR], 7.80; 95% CI, 3.90-15.60) and physical disability (39.6% vs 20.1%; AOR, 2.60; 95% CI, 1.26-5.39). Although Cambodians were hopeful that the trials would promote justice, 87.2% (n = 681) of those older than 35 years believed that the trials would create painful memories for them. In multivariate analysis, respondents with high levels of perceived justice for violations during the Khmer Rouge era were less likely to have probable PTSD than those with low levels (7.4% vs 12.7%; AOR, 0.54; 95% CI, 0.34-0.86). Respondents with high levels of desire for revenge were more likely to have probable PTSD than those with low levels (12.0% vs 7.2%), but the difference was not statistically significant in the multivariate analysis (AOR, 1.76; 95% CI, 0.99-3.11). Probable PTSD is common and associated with disability in Cambodia. Although Cambodians had positive attitudes toward the trials, most were concerned that the trials would bring back painful memories. Now that the trials have begun, longitudinal research is needed to determine the impact of the trials on Cambodians' mental health.