Objectives: Various digital technologies are increasingly being introduced into the everyday life of children. It is possible that digital addiction has negative effect on psychosocial functions of children. What kind of specific effect does this new "digital environment" have for children? The goal of this research is to check the hypothesis that there is relationship between computer game addiction and low mood in 10year-old children. Methods: We used questionnaire for parents to reveal children with computer game addiction. Experimental group consisted of 30 10-year-old children with computer game addiction. Control group consisted of 30 children without computer game addiction. The children from experimental and control group were matched for gender. We used Revised Children's Anxiety and Depression Scale (RCADS) for assessment of separation anxiety disorder, social phobia, generalized anxiety disorder, panic disorder, obsessive compulsive disorder, and low mood (major depressive disorder) in children (Child Self-Reported). Results: We used Spearman correlation. Analysis has revealed the significant (p,.05) positive correlation between level of computer game addiction and low mood in children. However, we did not find the correlation between level of computer game addiction and other scales of RCADS. Conclusions: It can be assumed that there is relationship between computer game addiction and low mood in 10-year-old children. However, we need to do additional research using experimental design to approve the hypothesis that computer game addiction can cause the low mood in children.