Community violence among the youth can lead to a number of adverse psychiatric outcomes including post-traumatic stress disorder (PTSD). However, little research has been conducted in non-Western countries to assess this problem. This study aims to fill the void by assessing the lifetime exposure to traumatic events and burden of probable PTSD among university students in Karachi, Pakistan. A cross-sectional study was conducted at four private institutions in Karachi. Self-administered questionnaires were filled out by 320 students. Lifetime exposure and symptoms of PTSD were assessed using modified Composite International Diagnostic Interview (CIDI) and Post-Traumatic Stress Disorder Checklist-Civilian Version (PCL-C) questionnaires, respectively. A PCL-C score of 44 or above was used as cutoff for probable PTSD. Pearson chi-square test was used to assess the association between PTSD and different variables at a level of significance of 5%. Ninety-three percent of the respondents reported having lifetime exposure to at least one traumatic event with sudden unexpected death of a loved one (n = 187) and assaultive violence (n = 169) being the commonest reported traumatic events. Positive association for PTSD was seen with enduring physical attacks and motor vehicle accidents. Over a quarter of the students screened positive for probable PTSD, among them almost one third were male and 17% were female. Our results indicate a high exposure to violent events and elevated rates of lifetime PTSD among urban youth. Reduction in violence and better access to mental health facilities is warranted to decrease the health burden of PTSD in Pakistan.