Objective: ADHD in adolescents and low level of parental monitoring have been associated with increased risk-taking behavior. The present study examined whether parental knowledge of the child’s whereabouts mediates the correlations between adolescent ADHD symptoms and risk-taking behavior. Method: Ninety-two adolescents and their parents completed questionnaires assessing perceptions of parents’ monitoring, engagement in risk-taking behaviors, and ADHD symptoms. Results: Greater engagement in risk-taking behavior correlated with higher levels of ADHD symptoms and decreased parental monitoring. Mediation analysis revealed both direct effect of ADHD symptoms on risk-taking behavior and an indirect effect mediated by level of parental knowledge. Conclusion: These findings suggest that parental knowledge is negatively affected by the presence of ADHD symptoms, and may in turn lead to risk-taking behavior. The findings emphasize the need to target parenting and in particular parental knowledge of the child’s whereabouts to reduce risk-taking behaviors among youth with ADHD.