BACKGROUND: Not everyone who experiences a trauma develops posttraumatic stress disorder (PTSD). The aim of this study was to determine the risk and resiliency factors for this disorder in a sample of people exposed to trauma. METHOD: Twenty-five people who had developed PTSD following a trauma and 27 people who had not were asked to complete the Posttraumatic Stress Diagnostic Scale, the Coping Inventory for Stressful Situations, and the State-Trait Anxiety Inventory. In addition, they completed a questionnaire to provide information autobiographic and other information. ANALYSIS: Five variables that discriminated significantly between the two groups using chi-square analysis or t-tests were entered into a logistic regression equation as predictors, namely, being female, perceiving a threat to one's life, having a history of sexual abuse, talking to someone about the event, and the "intentionality" of the trauma. RESULTS: Only being female and perceiving a threat to one's life were significant predictors of PTSD. Taking base rates into account, 96.0% of participants with PTSD were correctly classified as having the disorder and 37.0% of participants without PTSD were correctly classified as not having the disorder, for an overall success rate of 65.4% CONCLUSIONS: Because women are more likely than men to develop PTSD, more preventive measures should be directed towards them. The same is true for trauma victims (of both sexes) who feel that their life was in danger