This study examined the relationship between media violence exposure and Attention-deficit/hyperactivity disorder (ADHD)-related behaviors. Using survey (parent-reported) and genetic data of 1,612 Dutch children (aged 5 to 9 years), we examined genetic disposition as a possible cause of individual differences in children's use of and susceptibility to media violence. The gene variant of interest was the 5-HTTLPR polymorphism, which has been associated with ADHD-related behaviors in previous research. Results showed that the “long” variant of the gene polymorphism was related to greater violent media use, which in turn was related to more ADHD-related behaviors. The 5-HTTLPR genotype did not moderate the effect of media violence on ADHD-related behaviors. This study provides insight into the role of genetic factors in media effects.