SummaryPosttraumatic stress disorder (PTSD) is an anxiety disorder, currently defined by the coexistence of three clusters of symptoms (re-experiencing, avoidance and hyperarousal) persisting for at least one month, in survivors of a traumatic event.The disorder has won a central place in current discourse in mental disorders, among many reasons for such success are;1. Extended focus of modern psychiatry on non-psychotic disorders and their impact on individuals’ autonomy and wellbeing.2. Increased social awareness regrading human rights, violence, disasters and their consequences.3. A recent emphasis of the neurobehavioral sciences on brain plasticity and gene expression, and the paradigmatic role of traumatic events as triggering such reactions.Aim of the work:1. To determine the prevalence of traumatic events and PTSD among Egyptian adolescents and young adults.2. To determine the most frequent types of traumatic events.3. To determine the sosciodemographic factors which are associated with traumatic events and PTSD.4. to investigate the comorbidity of traumatic events and PTSD with other psychiatric disorders.Subjects and Methods:The participants in this study are 1239 subjects aging 14-24 years from Mit ghamr secondary schools and Zagazig university were investigated for traumatic events using a list of 19 traumatic events operationalize DSM-IV definition and investigated for PTSD and hypothesized comorbid psychiatric disorders by Mini-International Neuropsychiatric Interview and these findings are correlated to sociodemographic data.The study carried out from 2002-2004.Results:From the total sample: 171 subjects (13.8%) gave a history of exposure to traumatic events; 123 subjects of them (82%) exposed to one traumatic event and 48 subjects (28%) exposed to two or more traumatic events.The most freuent traumatic events are learning that a close friend or relative is exposed to traumatic event and also sudden, unexpected death of a close friend or relative, and the least frequent traumatic events are assaultive violence especially rape, held captive, tortured and kidnapped.Fifteen subjects only met the diagnostic criteria of PTSD, this represents (1.2%) of the total sample and (8.7%) of the trauma subsample.Males and subjects of families have low household income are more prone to exposure to traumatic events, but no significant difference according to residence, level of education and marital status of parents. Females, subjects of divorced parents and subjects exposed to more than one traumatic event have more risk in development of PTSD but no significant difference according to residence, level of education and household income.There is significant comorbidity between traumatic events and each of: generalized anxiety disorder (5.3%), panic disorder (2.3%) and agoraphobia (2.3%), but no significant comorbidity between traumatic events and each of: major depressive disorder, dysthymia, social phobia, obsessive compulsive disorder, substance abuse or eating disorders.There is significant comorbidity between PTSD and other psychiatric disorders (80%); individually, major depressive disorder (60%), dysthymia (13.3%), generalized anxiety disorder (40%), panic disorder (26.7%), social phobia (26.7%), agoraphobia (13.3%), obsessive compulsive disorder (13.3%), and substance abuse (6.7%) but no significant comorbidity with eating disorders.RecommendationThe observation that 1.2% of the total sample and 8.7% of trauma subsample are suffering from posttraumatic stress disorder (PTSD) and subsequent increased risk of comorbidity of other mental disorders clearly demonestrate the importance of this disorder, specially with increased rate of traffic accidents, terroristic attacks and natural disasters.Most of these cases to be noticed need more attention to this illness, more seminars, lectures and studies.PTSD is rcommended to be studied in wider range of age and also in more broad community groups as it helps in better detection and management of this broadening illness.Egyptian scales must be constructed and accommodate for using it in our environment, due to variations between Egyptian and other communities , and altered types of traumatic events.