Introduction: Vaccination is thought to be one of the most important medical advances. The public generally believes that vaccines are safe and effective, although the ingredients of vaccines are unknown and foreign to most people. The vaccination schedule has changed in line with the contagiousness of the diseases we are trying to prevent with vaccination and the level of vaccination coverage, which has remained the same in the last years. Purpose: The aim of the thesis is to explain and determine how the vaccination programme developed and improved throughout the years, but also to determine the ingredients in vaccines based on the literature overview. The purpose is also to establish whether some ingredients are potentially harmful and wheather the components of vaccines have changed over the years. Methods: The research was based on a descriptive research method combining a scientific and research literature overview. In addition, the literature was limited to English and Slovenian languages and searched using different search engines, such as COBISS, CINAHL, DiKUL, PubMed, ScienceDirect, and Google Books. Results: Based on the reviewed literature, it was found that the vaccination schedule in Slovenia changed and improved throughout the years on the basis of the contagiousness of the diseases and the level of vaccination coverage. Most of the ingredients found in vaccines are harmful or even toxic to humans, and the second problem is contamination of vaccines with viruses and bacteria that should not be among the components of vaccines. Most of the ingredients found in vaccines are harmful or even toxic to humans. The problem is also contamination of vaccines with viruses and bacteria that should not be among the components of vaccines. However, the ingredients in vaccines have not changed significantly throughout the years and remain the same with the exception of the toxic Thiomersal, which was removed. Discussion and conclusion:The history of vaccinationin Slovenia is consistent with the basis of the contagiousness of the diseases and the level of vaccination coverage on the basis of which the vaccination schedule is remaining the same for 13 years.The ingredients of vaccines should be more thoroughly examined and their toxicity should be generally known. The amounts of aluminum found in today's vaccines are alarming, so there will be a increased need for high quality vaccines as the years go by because the society, which has gained knowledge regarding the vaccine composition, has already started to put pressure over the issue. If we want a healthy society, providing information is crucial because the quality of vaccines will only improve as a result of public pressure.