This study describes the public health burden of trauma exposure and posttraumatic stress disorder (PTSD) in relation to the full range of traumatic events to identify the conditional risk of PTSD from each traumatic event experienced in the Mexican population and other risk factors. The representative sample comprised a subsample (N = 2,362) of the urban participants of the Mexican National Comorbidity Survey (2001−2002). We used the World Health Organization's Composite International Diagnostic Interview (CIDI) to assess exposure to trauma and the presence of PTSD according to the Diagnostic and Statistical Manual of Mental Disorders (4th ed.; DSM‐IV; American Psychiatric Association, ) in each respondents’ self‐reported worst traumatic event, as well as a randomly selected lifetime trauma. The results showed that traumatic events were extremely common in Mexico (68.8%). The estimate of lifetime PTSD in the whole population was 1.5%; among only those with a traumatic event it was 2.1%. The 12‐month prevalence of PTSD in the whole population was 0.6%; among only those with a traumatic event it was 0.8%. Violence‐related events were responsible for a large share of PTSD. Sexual violence, in particular, was one of the greatest risks for developing PTSD. These findings support the idea that trauma in Mexico should be considered a public health concern.