The aim of this study was to examine differences between motor vehicle accident (MVA) victims diagnosed retrospectively with Acute Stress Disorder (ASD) and subsequent Post-Traumatic Stress Disorder (PTSD), and MVA victims with only PTSD. A total of 14 ASD subjects and 28 PTSD subjects (matched on age and on sex) were compared on subjects' levels of functioning and symptom severity at three time-points: pre-MVA, 1-4 months post-MVA (initial assessment), and 6 months post initial assessment. Fourteen non-MVA subjects were included as controls in the analyses for pre-MVA differences and presence of psychopathology at time of initial assessment. ASDs had higher rates of previous mood disorders (other than major depression), previous AXIS-I disorders, and previous AXIS-II disorders than did PTSDs. No differences existed between the groups at 6-month follow-up. These results provide clinically useful information regarding characteristics that predispose people to develop ASD in the aftermath of a trauma. Previous research with trauma victims has demonstrated dissociative symptoms to be associated with higher PTSD symptom severity and longer symptom duration, but our follow-up results suggest that ASD, which is characterized by dissociative symptomatology, is not indicative of poorer outcome in MVA victims.