Attention deficit hyperactivity disorder (ADHD) is a common developmental disorder. This study tested the hypothesis that children with ADHD exhibit a higher caries prevalence and poorer oral health behavior than children in a control group. Twenty-one children with ADHD and a control group of 79 children, all aged 13 yr, underwent a clinical dental examination and completed two questionnaires on dietary habits and dental hygiene habits. Differences between the groups regarding decayed, missed, or filled surfaces, decayed surfaces, initial caries lesions, and gingival inflammation were non-significant. Forty-eight percent in the ADHD group brushed their teeth every evening compared with 82% in the control group. The corresponding frequencies for brushing the teeth every morning were 48% and 75%. Children with ADHD were 1.74 times more likely to eat or drink more than five times a day than children in the control group. In conclusion, at age 13, children with ADHD do not exhibit a statistically significantly higher caries prevalence but do have poorer oral health behavior than children in a control group. The intervals between dental examinations of children with ADHD should be shorter than for other children to prevent a higher caries incidence in adolescence because of their oral health behavior.