Attempts to boost the effectiveness of psychotherapy by combining it with psychotropic medications such as antidepressants or anxiolytics have shown rather limited effects and acute gains have tended to be lost when the drug is discontinued. In recent years, however, there has been growing interest in studying pharmacological interventions that may boost the effectiveness of psychotherapy not by treating symptoms directly but by catalyzing the psychotherapeutic process itself. These approaches use isolated doses of drugs in conjunction with psychotherapy sessions rather than ongoing daily drug doses. Thus, after a hiatus of over 20 years, “psychedelic” compounds such as MDMA or psilocybin are once again becoming subjects of serious, well controlled clinical studies. This presentation will illustrate the neurophysiological and –psychological rationale of MDMA-assisted psychotherapy for PTSD, as well as the nature of the therapeutic process with clinical vignettes. Outcome data from the completed US and ongoing Swiss studies will be presented, which suggest a promising future for this model of drug-assisted psychotherapy.