The human immunodeficiency virus (HIV) is the cause of an infectious, sexually transmitted, incurable disease. HIV in its advanced and final stages causes acquired immunodeficiency syndrome, AIDS. The human immunodeficiency virus is most often transmitted through sexual intercourse with an HIV-positive person, sharing syringes and needles, and from an HIV-positive mother to her child during pregnancy and childbirth. According to estimates by the World Health Organization (WHO), around 25 million people worldwide have died since the beginning of the AIDS epidemic. In the Republic of Croatia, the HIV/AIDS Registry monitors and records the frequency of HIV infection, as well as AIDS-related deaths. The aim of this paper is to present in more detail the human immunodeficiency virus (what is HIV, as it is diagnosed and treated), to show how HIV-positive people live with stigma, and how education can reduce the number of newly infected people and the stigmatization of already infected people. The goals of this research include the assessment of the knowledge and attitudes of secondary school students in Sisačko-moslavačka County about human immunodeficiency virus, and a comparison of the knowledge and attitudes of Srednja škola Viktorovac students (nurse/general care technician) with other secondary schools in Sisačko-moslavačka County about human immunodeficiency virus. Students from the following secondary schools in the Sisačko-moslavačka County participated in the research: Tehnička škola Sisak, Ekonomska škola Sisak, Industrijsko-obrtnička škola Sisak, Srednja škola Viktorovac (nurse/general care technician). 229 students between the ages of 15 and 19 participated in the research. The research showed that despite students' positive self-assessment of their knowledge about HIV, only 64% of students correctly answered how HIV is transmitted, and more than 50% of students answered that HIV can be cured. Taking these findings into account, we should ask ourselves whether it is time for health education to be introduced in secondary schools and implemented continuously. These findings clearly indicate the need for systematic education, and the above data can serve as a guideline and incentive for high school institutions to start introducing health education into classes before it is too late.