Post-Traumatic Stress DisorderThe history of medicine, occupational health and psychiatry has been punctuated by recurring themes related to what is now called post-traumatic stress disorder (PTSD). For several centuries, aversions to, and maladies from, extremely stressful events have been described, but clues to their causes have only recently been discovered. Previously called ‘railway spine’, ‘battle fatigue’ and ‘shellshock’, post-traumatic stress syndromes have been a topic for speculation and diagnosis when no other label will suffice. Over the past 30 years, investigation of traumatic stress has exploded and a substantial mass of research evidence has been gathered. Initially, this was primarily due to an interest in the uniquely pervasive symptoms of Vietnam veterans. However, tragedy is not limited to war and the development of PTSD is not limited to soldiers. The recent proliferation of PTSD research in diverse populations has added to the understanding of PTSD as a mental health disorder, to our understanding of human reactions to stress, and to knowledge about possible links between mental and physical health.