Study Comparing Three Doses of MDMA Along With Therapy in Veterans With Posttraumatic Stress Disorder

Inclusion Criteria: * Be diagnosed with chronic PTSD, duration of 6 months or longer resulting from traumatic experience during military service; * Have a CAPS score showing moderate to severe PTSD symptoms; * Have had at least one unsuccessful attempt at treatment for PTSD either with talk therapy or with drugs, or discontinuing treatment because of inability to tolerate psychotherapy or drug therapy. * Are at least 18 years old; * Must be generally healthy; * Must sign a medical release for the investigators to communicate directly with their therapist and doctors; * Are willing to refrain from taking any psychiatric medications during the study period; * Willing to follow restrictions and guidelines concerning consumption of food, beverages, and nicotine the night before and just prior to each experimental session; * Willing to remain overnight at the study site; * Agree to have transportation other than driving themselves home or to where they are staying after the integrative session on the day after the MDMA session; * Are willing to be contacted via telephone for all necessary telephone contacts; * Must have a negative pregnancy test if able to bear children, and agree to use an effective form of birth control; * Must provide a contact in the event of a participant becoming suicidal; * Are proficient in speaking and reading English; * Agree to have all clinic visit sessions recorded to audio and video * Agree not to participate in any other interventional clinical trials during the duration of this study. Exclusion Criteria: * Are pregnant or nursing, or if a woman who can have children, those who are not practicing an effective means of birth control; * Weigh less than 48 kg; * Are abusing illegal drugs; * Have used ecstasy (material representing itself as MDMA) more than 5 times or at least once in the last 6 months; * Are unable to give adequate informed consent; * Upon review of past and current drugs/medication must not be on or have taken a medication that is exclusionary; * Upon review of medical or psychiatric history must not have any current or past diagnosis that would be considered a risk to participation.