The last two decades have seen a massive increase in innovation research relating to drugs that were (and in most cases still are) banned under the UN Conventions and national drugs legislation. Many of these drugs, particularly the psychedelics such as psilocybin and LSD, had been shown to have significant benefits for mental health and addictions before they were banned in the 1960s/70s These early observations have since been confirmed with new studies of psilocybin in depression and addictions. More recently cannabis, ketamine, and MDMA have revealed efficacy in disorders such as PTSD, depression, and addiction. We are now in a new era of psychedelic-psychotherapy that offers a major advance for many patients who hitherto have not responded well to conventional treatments. Also, brain imaging research now helps us understand how these drugs work to facilitate the person engaging with the therapeutic process and why the impact of just one or two psychedelic interventions can lead to long-term benefits.