Vaccination against an infectious disease is a medical procedure aimed at inducing a specific protective immune response against the causative agent of an infectious disease before the disease appears. The development of vaccines is one of the most significant milestones in the history of medicine. Active immunization has achieved a sharp reduction in mortality and morbidity from diseases for which vaccination is mandatory. Although vaccination is one of the safest medical procedures, there is a risk of side effects. Side effects are mostly mild, but serious side effects that can have long-term consequences are rare. The official position of medicine is that the benefits of vaccination far outweigh the possible risks. Opinions on vaccination have been divided from the very beginning, but in recent decades this controversial topic has been increasingly debated. Refusal to vaccinate for non-medical reasons, but because of concerns about its safety, justification, effectiveness and ethics results in suboptimal vaccination coverage. Vaccines can prevent infectious diseases in vaccinated individuals and prevent their spread in the population and in susceptible individuals who cannot be vaccinated due to their age or medical condition. To be successful, vaccination programs depend on high levels of vaccination uptake. Not only does this provide direct protection for vaccinated individuals, but it also promotes indirect protection for the entire community. In recent years, the number of mandatory vaccinations in the Republic of Croatia has decreased, and this research aims to determine the attitudes of parents about children's vaccinations. During the preparation of the final paper, online research was conducted on social networks in the period from April 8 to May 30, 2022. The research was conducted on a sample of 1839 participants. The results showed that more than half of the participants 1131 (61.5%) advocate vaccination, 402 (21.9%) participants are undecided, while 306 (16.6%) participants are against vaccination. The legal obligation to vaccinate the child/children according to the regular vaccination calendar is fulfilled by the majority of participants 1634 (88.9%), and a smaller number of 205 (11.1%) participants do not fulfill the legal obligation to vaccinate the child/children, which is not enough to achieve collective immunity. Parents who come from urban areas and who have a higher level of education have more positive attitudes about the mandatory vaccination of their child/children.