Informant- and gender-specific characteristics of Oppositional Defiant Disorder (ODD) and how these might relate to patterns of comorbidity need to be further clarified. We collected data from 7,007 children (aged 7–9) who participated in the Bergen Child Study (BCS), an ongoing population-based study of children’s development and mental health. A questionnaire containing the DSM-IV behavioral descriptions of ODD was distributed to parents and teachers. Co-occurring symptoms of mental health problems were measured by the Strengths and Difficulties Questionnaire (SDQ). The boys (n = 122) and girls (n = 41) with symptomatic ODD had an increased risk of co-occurring emotional symptoms, hyperactivity or inattention and peer problems, as compared to their peers without symptomatic ODD. The impact of symptomatic ODD was higher for boys than girls in teacher reported SDQ ratings, except for emotional symptoms. There were no significant interaction effects of gender in parent SDQ ratings. Our results are contrary to the gender paradox hypothesis, which states that co-occurring symptoms of mental health problems are more frequent among girls with ODD as compared to boys with ODD.