The MDMA-assisted psychotherapy session will be conducted by a male and female co-therapist team, one a psychiatrist and the other a psychiatric nurse. Vital signs (blood pressure, pulse and body temperature) and psychological distress will be measured throughout the experimental session. After the experimental session they will spend the night in the clinic with an attendant on duty, and complete a measure of alterations in consciousness, the States of Consciousness Questionnaire (SCQ) on the evening or day following the experimental session. Participants will meet with the investigators the next morning for an integrative psychotherapy session before leaving the clinic. During integrative psychotherapy sessions they will receive support in integrating their experiences and insights from the MDMA-assisted psychotherapy session. There will be daily phone contact with one of the investigators for 7 days after the experimental session. Symptoms of PTSD, depression and general function will be assessed two months after the experimental session. There will be a long-term follow up with repeated outcome measures 12 months after the experimental session