The Peritraumatic Dissociative Experiences Questionnaire (PDEQ) is a widely used measure of peritraumatic dissociation, and is presumably a unidimensional construct. Two hundred forty-seven individuals admitted to five hospitals after traumatic injury were administered the Clinician Administered PTSD Scale, the Hospital Anxiety and Depression Scale, and the PDEQ. Factor analysis indicated that the PDEQ involved two factors containing four items each: one factor (altered awareness) indexes alterations in awareness and the other (derealization) reflects distortions in perceptions of the self and the world. Only the derealization factor was associated with acute stress, anxiety, and depression symptoms. Cross-validation with independent data provided only partial support for the 2-factor structure model. These data indicate that peritraumatic dissociation may involve two distinct constructs.