Although a number of studies have been conducted over the past decade on the association between screen time and developmental outcomes in children, most studies mainly deal with the problem of obesity and physical fitness of children, while the studies on the association of screen time and mental health are rare, and there is especially a lack of research concerning internalized problems in children. Early detection of psychological problems is one of the foundations of later successful prevention and treatment, and some research shows that as many as 20% of children, including kindergarten children, exhibit certain psychological difficulties, and also that certain behaviours of preschool children are associated with various mental disorders and problems in adulthood. The aim of this research was to examine the correlation between total screen time and some indicators of the mental health of children - emotional reactivity, anxiety/depression, somatic problems, withdrawal, sleeping problems, attention problems, and other problems, in a sample of Croatian children attending kindergartens. We also examined moderating effects of child’s involvement in other activities, such as physical activity, playing with peers, overall outdoor activities, and time spent in other activities. In this paper, potential risk and protective factors related to screen time were investigated in preschool children, with a focus on their mental health.