The aim of this study was to examine the attitudes of high school students toward schizophrenia, depression and posttraumatic stress disorder and explore how formal education, gender and religious affiliation affected those attitudes together with the education and marital status of their parents. A total of 156 fourth-grade students from three secondary schools in the Primorje-Gorski Kotar County participated in the study: 57 medical nursing students from the Medical High School in Rijeka, 41 students from the Salesian Classical High School in Rijeka and 58 students from the Maritime High School in Bakar. A demographic questionnaire and a questionnaire on attitudes toward patients with mental illnesses were used. The results have shown that there was a statistically significant difference in the attitudes of high school students toward psychiatric patients based on the secondary school they attended, showing that students from the Medical school had more positive attitudes toward the mentally ill than others, and there was also a statistically significant difference regarding the attitudes toward specific psychiatric illnesses. High school students had the most negative attitudes toward schizophrenia and the least negative toward depression. There was no difference in the attitudes of high school students with regard to their religious affiliation and marital status of parents. The differences in attitudes based on the parents’ levels of education were statistically significant only regarding the attitudes toward schizophrenia – the results showed that high school students whose mothers were highly educated had more negative attitudes. High school differences in attitudes based on the gender of the participants could not be established since the majority of participants from the Medical High School were female nursing students, while male students were the majority at the Maritime High School. Comparison of data obtained from high school students by gender did not reveal differences in attitudes based on gender. In order to explore the difference in attitudes based on gender, it would be necessary to extend the study to a much larger number of respondents and exclude students from medical schools. Based on the results of this study, it can be concluded that the attitudes of high school students toward psychiatric patients were greatly influenced by formal education, i.e. acquired knowledge on psychiatric illnesses, since high school students from the Medical high school showed the smallest extent of stigmatization toward psychiatric patients, most likely due to the expertise and knowledge obtained through their education. Therefore, we can conclude that in the future more effort should be put into education on psychiatric disorders and mental health in general, and only then could we expect less stigmatization toward psychiatric patients in our society.