Vaccination is the most effective method to prevent infectious diseases, a Public Health project from last century that saves two to three million children per year across the world. Even though vaccination is legally mandatory in many countries and despite the evident epidemiological indicators of vaccine’s efficiency that is manifested in much lower incidence of preventable paediatric infectious diseases (smallpox eradication, polio eradication in big part of the world), there is a increasing number of parents that refuse to vaccinate their children. This results in an increase of non-vaccinated children and occurrence of major or minor epidemics of preventable infectious diseases. Nowadays, there is a big trend among parents revolving around non vaccination of their children because of the side effects of vaccinations. Moreover, parents refuse to vaccinate their children due to fear and lack of reliable information. Internet is the most used platform for sharing information in 21st century. A lot of parents try to obtain information via social media, they make online groups where they exchange experiences and stories and where they consult with amateurs who do not work in medicine on whether they should vaccinate their child. The resistance to vaccination is increasing each day as online groups and their members are becoming larger. The parent-paediatrician partnership is the most prominent in the implementation of the vaccination program. Parents that are well informed by a paediatrician about diseases their children are being vaccinated against, importance of vaccination, type of vaccine as well as possible side effects, will not have any doubts or fears and will agree to vaccinate their child. When the World Health Organisation launched immunization programme in 1947, there were less than 5% of children in the world vaccinated against 6 aimed diseases. Today, there are more than 80% of children in the world vaccinated against those diseases before age of 1. There are more than 130 million children vaccinated per year and it is estimated that 3 million children are saved due to vaccinations per year. In Croatia, it is mandatory to vaccinate against: tuberculosis, diphtheria, tetanus, whooping cough, polio, diseases caused by Haemophilus influenzae type B, hepatitis B, pneumococcus, smallpox, mumps and measles. Vaccination against mentioned diseases is carried out routinely and continuously and it is important to emphasise that we need to continue vaccinating in order to maintain and improve achieved results.