Substances of plant origin have been used to induce hallucinations for a long time, in religious ceremonies and rituals as well as in pain relief. Psilocybin and psilocin naturally occur in the fungal genus Psilocybe. Due to the psychedelic effects and relative harmlessness of these substances and the fact that they do not cause physical addiction, psilocybin and psilocin recently have been increasingly replacing synthetic psychodysleptics, such as diethylamide D-lysergic acid. Both compounds as psychoactive substances are illegal, but psilocybin, in addition to psychotropic action, also shows positive effects, which from a medical point of view indicate its therapeutic potential and capacity for use in therapy. However, poisoning by psilocin and its derivatives is still a major clinical and social problem, mainly among young people, which is why quick and reliable identification of these substances is very important. Traditional ways of assigning the sample to a particular taxon, such as morphological and biochemical analysis or palynological and sporological studies, are not very universal and often do not provide clear results. Credibility, high speed and lower cost of DNA analysis make genetic methods more often used to determine the species of fungi. These methods are random amplification of polymorphic DNA (RAPD), amplified fragment length polymorphism (AFLP) and high resolution melting (HRM). Moreover, analysis of the regions ITS1 and nLSU was suggested as a valid method for application in the molecular taxonomy of fungi for forensic purposes. Modern methods of identifying psilocybin and psilocin in fungi and biological material are: zone capillary electrophoresis, high performance liquid chromatography, gas chromatography and liquid chromatography coupled with mass spectrometry. The mentioned methods are successfully used for the identification of psychoactive substances in fungi as well as in blood and urine samples.