Background: The author prospectively examined the power of persistent dissociation in predicting acute and chronic posttraumatic stress disorder symptoms (PTSD) in psychologists, psychotherapists, crisis intervention teams and clergymen after a disaster. Methods: 135 psychosocial disaster workers were assessed (6 weeks and 6 months after the catastrophe) with the Acute Stress Disorder Scale (ASDS), the Posttraumatic Stress Diagnostic Scale (PDS) and the German short version of the Dissociative Experience Scale (FDS-20). Correlational analysis and a hierarchical multiple regression analysis were conducted. Results: Persistent dissociation and acute stress symptoms were correlated with later acute and chronic PTSD diagnosis. Together, persistent dissociation and acute stress symptoms accounted for 74% (m)/36% (w) of the acute and 58% (m)/44% (w) of the variance in PTSD symptoms. Conclusions: The results support that persistent dissociation is a main predictor of acute and chronic posttraumatic stress symptoms in disaster workers.