BACKGROUND: Recent studies show that individual single-session psychological debriefing does not prevent and can even aggravate symptoms of post-traumatic stress disorder (PTSD). AIMS: We studied the effect of emotional ventilation debriefing and educational debriefing v. no debriefing on symptoms of PTSD, anxiety and depression. METHOD: We randomised 236 adult survivors of a recent traumatic event to either emotional ventilation debriefing, educational debriefing or no debriefing (control) and followed up at 2 weeks, 6 weeks and 6 months. RESULTS: Psychiatric symptoms decreased in all three groups over time, without significant differences between the groups in symptoms of PTSD (P=0.33). Participants in the emotional debriefing group with high baseline hyperarousal score had significantly more PTSD symptoms at 6 weeks than control participants (P=0.005). CONCLUSIONS: Our study did not provide evidence for the usefulness of individual psychological debriefing in reducing symptoms of PTSD, anxiety and depression after psychological trauma.