This systematic review examines the prevalence and course of post-traumatic stress disorder (PTSD) following exposure to disasters. It includes 284 peer-reviewed studies published between 1980 and February 2007, categorized into human-made disasters (n=90), technological disasters (n=65), and natural disasters (n=116). The review finds that PTSD is a common psychiatric disorder following disasters, with high prevalence among survivors, first responders, and disaster workers. PTSD prevalence varies by disaster type, with higher rates among those directly exposed to traumatic events. The course of PTSD is generally characterized by a decline over time, though some studies suggest a late onset or persistence in certain populations. The review highlights methodological limitations, including the lack of longitudinal studies and variability in assessment tools. It also notes that PTSD is more prevalent among high-risk groups, such as low-income minorities, and that indirect exposure to disasters may also contribute to PTSD. The review emphasizes the need for further research to better understand the course of PTSD and to develop effective interventions. It concludes that PTSD is a significant burden following disasters, with implications for public health planning and disaster response.This systematic review examines the prevalence and course of post-traumatic stress disorder (PTSD) following exposure to disasters. It includes 284 peer-reviewed studies published between 1980 and February 2007, categorized into human-made disasters (n=90), technological disasters (n=65), and natural disasters (n=116). The review finds that PTSD is a common psychiatric disorder following disasters, with high prevalence among survivors, first responders, and disaster workers. PTSD prevalence varies by disaster type, with higher rates among those directly exposed to traumatic events. The course of PTSD is generally characterized by a decline over time, though some studies suggest a late onset or persistence in certain populations. The review highlights methodological limitations, including the lack of longitudinal studies and variability in assessment tools. It also notes that PTSD is more prevalent among high-risk groups, such as low-income minorities, and that indirect exposure to disasters may also contribute to PTSD. The review emphasizes the need for further research to better understand the course of PTSD and to develop effective interventions. It concludes that PTSD is a significant burden following disasters, with implications for public health planning and disaster response.