Objective Trauma is reported by 70% of the global population and 4% of those exposed develop post-traumatic stress disorder (PTSD), but data from Indigenous populations are limited. We aimed to determine the prevalence, types and age of occurrence of traumatic events among community-living Indigenous Australians and associations with PTSD. Design Lifetime trauma and PTSD were quantified among a broadly representative sample of 544 Indigenous participants using a diagnostic clinical interview. Logistic regression examined predictors of PTSD. Setting Metropolitan, regional and remote areas of Southern Queensland and Northern New South Wales. Participants Indigenous Australians 18 years and older. Outcome measures Prevalence of traumatic life events and risk of PTSD. Results 64.9% of participants (standardised prevalence 62.6%) reported lifetime trauma, with more than one trauma category in 62.3%. Females reported 2.3 times more sexual violence, otherwise no gender differences existed. The prevalence of four common trauma categories were 1.7-3.0 times higher than in the Australian population; physical violence being the highest relative risk. Although overall childhood trauma was not increased, sexual or physical violence before age 15 was twice more common than in the Australian population. The standardised prevalence of 12-month PTSD was 13.3% (95% CI 10.4 to 16.1), 16.1% (95% CI 12.2 to 19.9) in females and 8.2% (95% CI 5.3 to 11.1) in males, three times the Australian rates. In multiple regression analysis, independent predictors of PTSD were female gender (OR 2.1), rural residence (OR 3.0), trauma under age 10 (OR 2.2), sexual (without physical) violence (OR 2.5), physical (without sexual) violence (OR 2.3), and both sexual and physical violence (OR 5.0). Conclusion Indigenous Australians are more likely to experience potentially harmful traumas and develop PTSD than other Australians. Mitigation of trauma among Indigenous Australians, particularly childhood exposure and sexual or physical violence, is essential to reduce their high burden of PTSD.