Active immunization or a vaccination is the procedure of introducing a specific antigen in the body that stimulates the development of a specific defense towards a particular cause of an infectious disease. The vaccination represents one of the greatest medical achievements in the twentieth century. It is one of the most effective and from the economic point of view most cost effective ways to protect both individuals and the entire population from some infectious diseases. The goal of this study was to investigate the attitude of parents towards their children's vaccinations. A voluntarily questioning which involved one hundred and twenty parents was conducted in two pediatric clinics of the “Health Center Zagreb West”. An anonymous questionnaire, containing twenty six questions used to estimate the attitude of parents towards their children's vaccinations, was used for the survey. The results showed that most of the parents have a positive attitude towards the vaccination of their children and also positive experiences with the previous vaccination of their children. Many of the parents think that vaccination should be mandatory and most of them would let their children be vaccinated even if there would be no legal obligation. Most of the parents get the information about children vaccination from the competent physician and via internet. Not all parents are fully and adequately informed about the vaccination of children, and what concerns them most are the side effects of the vaccine. There are no significant differences between the attitudes of parents towards children’s vaccination according to age, marital status, level of education, employment and monthly income of the family. However, there is a statistically significant difference in the attitude of parents towards children´s vaccination according to parents gender and the number of children in the family – especially among respondents which have only one child, compared to respondents who have three or more children. The majority of parents are satisfied with the information provided by the responsible doctors and nurses. Nevertheless, there is a need for a better communication between the health care employees and the parents as well as a better education of the parents and the general public about the benefits of vaccination.