The goal of this study is to examine levels of oppositional defiant disorder (ODD) and conduct disorder (CD) in four groups of children: attention-deficit/hyperactivity disorder (ADHD) only, anxiety only, ADHD and anxiety, and controls (i.e., non-ADHD youth). Although children with ADHD exhibit more ODD and CD than non-ADHD youth, it is unknown if anxiety is associated with increased or decreased ODD and CD in children with ADHD. We examined parent and teacher ratings of ODD and CD from the Disruptive Behavior Disorder Rating Scale in 203 school age children (ages 6-9); 70% were male, and 47% were Caucasian. Children were divided into four diagnostic groups based on ADHD and anxiety status from the Diagnostic Interview Scale for Children. According to parents, children with ADHD and anxiety had the highest levels of ODD/CD, followed by children with ADHD only (i.e., without anxiety). Children with anxiety only and controls had lowest ODD and CD scores, and these groups did not differ from each other. The same patterns were found according to teacher report, except that the anxiety only group had significantly lower levels of ODD than non-ADHD controls. Further, combined type ADHD youth with anxiety exhibited the highest levels of ODD and CD compared to all other groups. Comorbid anxiety may strengthen the association of ADHD and ODD/CD, particularly in the combined subtype. We discuss the importance of comorbid anxiety to the development of externalizing problems as well as potential explanatory factors underlying elevated ODD and CD among children with ADHD and anxiety. (Contains 1 table and 3 figures.)