Evidence is scarce regarding the prevalence of interparental discord in families of adolescents with attention-deficit/hyperactivity disorder (ADHD). Using data collected from adolescents with childhood ADHD and comorbid oppositional defiant disorder (ODD; n = 46) or conduct disorder (CD; n = 23), with childhood ADHD only (n = 26), and without ADHD (n = 88) and their mothers, maternal and adolescent reports of interparental discord were compared. Adolescents with ADHD + CD reported witnessing more frequent and unresolved interparental conflict than adolescents without ADHD and with ADHD only. Adolescents with ADHD + CD also indicated more frequent conflict than adolescents with ADHD + ODD. However, differences in conflict resolution were nonsignificant when household income was covaried, and maternal ratings of interparental discord did not differ across groups. Findings highlight the potential utility of adolescents with ADHD as informants of interparental relationship quality. (Contains 3 tables.)