This study assessed the trajectory of PTSD symptoms for three years in a sample of patients who survived severe accidental injuries. The sample comprised 121 severely injured patients aged 18 to 70 years who were recruited consecutively between January 1996 and June 2000 from the intensive care unit (ICU) at Zurich University Hospital, Switzerland. All the patients qualifying for the study had sustained accidental injuries that caused a life-threatening or critical condition requiring their referral to the ICU. Participants were first assessed within 1 month of the trauma and subsequently followed up after 6 months, 12 months, and 36 months. 90 patients participated in all four interviews.