Sexually transmitted infections are one of the leading infectious causes of acute illness, chronic health impairment and mortality; in addition, they can result in serious medical and psychological consequences. The causative infectious agents can be various microorganisms such as bacteria, viruses, fungi and parasites. When it comes to viral sexually transmitted infections, the most common ones are HIV/AIDS, hepatitis B, human papillomavirus, and genital herpes. HIV is a retrovirus that causes AIDS in the case of untreated infection, occurring in the advanced and final stages of HIV disease. The most common route of transmission of hepatitis B is the blood of an infected person, while less common transmission pathways can be sex or childbirth. For hepatitis B, the vaccine has been shown to be highly effective in preventing the disease, subsequently reducing the incidence of the disease in healthcare professionals. Human papillomavirus (HPV) is the most common viral sexually transmitted infection. Most HPV infections are self-limiting, and more than 100 types of HPV are known to date. What is important to highlight is how HPV-16 can cause cervical cancer, which is the second leading cause of death in women. Genital herpes (caused by herpes simplex virus type 2; HSV-2) is transmitted by close contact, and the virus enters the body via mucous membranes or injured skin, multiplying predominantly without any symptoms at the point of entry. HSV-2 is associated with genital infections, resulting in the development of painful vesicles upon entering the epithelial cells. Globally, more than 400 million adults suffer from sexually transmitted diseases annually, and about 60% of these infections occur in people under 25 years of age. Croatia is one of the countries with a low prevalence of viral hepatitis, i.e. by 2004 there were only about 200 registered individuals. HIV infection is still of paramount public health significance in Europe and the world, but has remained low since its inception in Croatia, with men prevailing among registered individuals. Sexually transmitted diseases are also important because of possible complications such as health disorders in women, ectopic pregnancy, and pelvic inflammatory disease as one of the most serious complications. When considering the prevention of sexually transmitted infections, it is pivotal to educate young people before engaging in sexual intercourse and to carry out vaccinations against certain diseases in order to reduce the risk and infection burden.