Prejudice and stigma are one of the common reasons for addicts to come into treatment too late, as well as for relapses and addicts leaving the treatment process, because these are the problems that addicts face when returning to their previous environment. At the same time, medical school students come to the Department of Addiction Treatment with fear and an attitude that they never want to work with addicts. Their attitude often changes after undergoing education and clinical practice, but the question is whether it can be said that they, as future health professionals, are willing, without prejudice, to spread knowledge further and work on addiction prevention. The aim of the research is to determine the attitudes of the third graders, fifth graders of the School of Nursing Vrapče before practice and the fifth graders after practice towards addicts and whether education affects the change of attitude, in order to improve the quality of education. The research starts from the hypothesis that there is a statistically significant difference between students attitudes before and after the internship at the Department of Addiction Treatment at the University Psychiatric Hospital Vrapče. The target group of the research were high-school medical students because they are the future health professionals who in their work are expected to make great effort and apply their knowledge to prevent stigma as well as to prevent the development of addiction. The study was conducted as a longitudinal study. A survey questionnaire was prepared for the purposes of this research. It was composed of questions from a standardized, already used questionnaire for stigma towards psychiatric patients. The selection of respondents was appropriate. The study involved 184 respondents, of which 66 third-graders, 65 fifth-graders before internship and 53 fifth-graders after internship. The research has shown that prejudices against addicts are reduced after meeting the addicts and working with them through clinical practice.