Childhood period is characterized by development of numerous psychological functions, but that development can be interfered by the influence of numerous factors. The goal of this research was to test the influence of certain factors on executive functions of preschool children. The main emphasis was put on the role of electronic media in development of child's executive functions as well as their possible connection with behaviour problems. The data were collected longitudinally in three phases during 2014, 2016 and 2018/2019 within a bigger project which started in 2014. 154 preschool children, who went in one of kindergartens in Rijeka, as well as 141 parents, took part in this final phase of the research. Each child was tested individually through a number of objective tasks which test executive functions while the parents filled in the Childhood Executive Functioning Inventory, Child Behaviour Checklist and several questions on the electronic media usage. Parents' evaluations of child's temperament, collected through The Early Childhood Behaviour Questionnaire, were taken from the first phase of the research. Descriptive analysis of the results proved wide accessibility of electronic media as well as some particularities in their usage. The analysis showed certain gender differences in a way that the girls used the tablets and smartphones more while the boys were taking the initiative in using computers, DVDs and game consoles. Majority of children spend between 1 and 2 hours a day in front of the screens and according to the parents more than half of them have limited time allowed to use the gadgets. Correlation analysis proved negative connection between the deficit of the working memory and the range of memorizing the numbers backwards. After looking into the differences in executive functions concerning the gender differences and time spent in front of the screen, the results show that the gender plays the main role while the objective measure of inhibition proves the importance of the interaction of the child’s gender and the time spent in front of the screen. Hierarchy regression analysis shows that the external and internal behaviour problems are significantly connected to the both factors of Evaluation scale of the executive functions of children – inhibition deficit as well as the deficit of the working memory. Conscious control and the inhibition deficit proved to be significant indicators which contribute to explaining of both dimensions of the behaviour problems in preschool children.