Objectives: Previous studies have examined the effect of parent-child relationships on conduct problems, but rarely are the mother-child and father-child relationships studied independently. The current study examined parent-child relationships and their connection to comorbid behaviors in children with Attention-Deficit/Hyperactivity Disorder (ADHD). More specifically, this study explored the mother-child and father-child relationship in children with ADHD, with an explicit focus on the aspects of the parent-child relationship that are related to more positive behavioral outcomes. Methods: A sample of 74 children with ADHD (aged 8-11 years) and their mothers (n = 74) and fathers (n = 37) participated in the current study and completed a variety of parenting and behavioral measures. A number of relationship factors, including parent- and child-reported levels of attachment were examined in connection to parental ratings of behavioral outcomes such as defiance, aggression, and conduct problems. Results: Results indicated that different aspects of the parent-child relationship for mothers and fathers were related to ratings of behavioral problems. Relational frustration was found to be a consistent predictor of negative ratings of behavior for both parents, while involvement was a predictor of more positive ratings of behavior for fathers only. Conclusions: A better understanding of the specific aspects of the mother-child and father-child relationship may play a role in helping to understand the link between parent-child relationships and behavioral concerns in children with ADHD. Implications for practice are highlighted with a particular emphasis on strengthening the parent-child bond in families with children with ADHD.