When infectious diseases are concerned, and most notably those in children, we can say that they are of utmost importance for social medicine and public health. According to the Croatian law, all children aged 5 to 7 are obliged to attend pre-school, which means they are constantly surrounded by other children. However, children often do not completely understand the importance of hygienic measures (like hand washing); moreover, they share toys which can be infected and are in constant interaction with each other. All of these factors hinder the adequate prevention of the spread of infectious diseases between young children. The main aim of this thesis was to cover the most common bacterial, viral, fungal and parasitic infections that are found in such young age, and to examine their frequency by using a survey. The survey was administered through between the December 31 and February 21 2020, and responses were acquired with the help of the social platform Facebook. A total number of survey responses was 379. The survey was intended for parents of children aged 5-7, and included all the regions of the Republic of Croatia. Since the main goal was to explore the frequency of infectious diseases on the wide scale, the survey included parents of 192 boys and 187 girls. A total of 182 children were aged 5, 135 children were aged 6, while 62 children were aged 7. According to the postulated hypotheses, the survey results have shown that the spread of disease is not affected by the parents’ education or children’s gender. The study has also shown that infections spread much easier in densely populated areas and during winter period, and also with children which attend preschool in groups that include more than 15 children. Finally, this research revealed that vaccination does not affect nor prevent the spread of infectious diseases among children. The role of the highly educated nursing personnel, working as the head of the health unit in a kindergarten, is primarily to observe the morbidity of children, to promote the children's health, as well as to improve and secure health care. The duty is also to provide education on the prevention of diseases between children, parents and employees who work at the facility. Finally, active participation in the lifelong education to protect the health of the institution is expected.