Diplomová práce se zabývá osobnostními charakteristikami uživatelů některých halucinogenů, konkrétně LSD a psilocybinu (halucinogenní houby). Specifika osobnosti uživatelů jsou nahlíženy z pohledu osobnostních rysů v rámci Pětifaktorového modelu Big 5. Uživatelé jsou porovnáváni s hodnotami populačních norem i mezi sebou s přihlédnutím k různým proměnným, které mohou být vypovídající o osobnosti uživatele. Mezi tím např. sociodemografické pozadí respondenta, pociťované změny vlivem halucinogenů a přítomnost mystického zážitku vlivem halucinogenů.Presented thesis deals with the personality characteristics of some hallucinogen users (LSD and psilocybin) in terms of the five-factor model of personality. The aim was to compare personality traits of users with a standard population and compare file surveyed between them in terms of other variables, including socio-demographic indicators, perceived personality changes and the presence of the phenomenon of mystical experiences during intoxication. Respondent selection was conducted by a snowball sample consisted of 83 people, mostly younger (M = 24). Data was collected using the NEO-PI-R and designed structured questionnaire. It was supposed to find increased dimension of Openness to experience, which was confirmed. The hypothesis of reduced Neuroticism was not adopted on the basis of nonmanifested significant difference. File proved to be slightly introverted. Most respondents reported positive personality changes due to use of hallucinogens in the case with LSD accompanied by increased values of Openness, which was also elevated in people who subjectively experienced a mystical experience. Based on the results it can not be directly confirmed that the changes were caused by hallucinogens in a measurable way, but their subjective significance for the participants is undeniable.