Research on psychotropics is gaining more popularity worldwide and support from drug regulatory agencies, which recognise the unmet medical needs of certain patient communities, such as patients with mental disorders and patients with cancer who experience depression. Cannabinoids and psilocybin have shown promising results in preclinical studies and clinical trials, but the current clinical evidence is scarce, and the regulatory requirements are strict due to high potential for drug abuse. The US FDA has recently released a draft, non-binding guidance on clinical trials with psychedelics. Europe is currently falling behind the US and Canada in terms of regulating psychotropic substances. The article provides a general introduction on conducting clinical trials with psychotropics and the regulatory requirements (as of October 2023) when submitting marketing authorisation application. In the near future, as more data becomes available, research on psychotropics will definitely shape the European regulatory landscape. Medical Writing. 2023;32(4):30–38. https://doi.org/10.56012/tsen2260