A lack of perseverance, poor attention, and poorly modulated behaviour are important criteria of Attention Deficit Hyperactive Disorder (ADHD). Instructions often have to be repeated, sometimes even by different family members before a child with ADHD attends and complies. We hypothesised that a child with ADHD might cause less disagreement in families with almost no conflicts. Responses to the Mannheim Parents Interview and teacher's form of the Conners scale completed by families of 15 boys (ages 6 to 12 years), diagnosed with ADHD were compared with those of a matched, healthy control group of 15 boys. Parents completed a form assessing the family's cooperation and child-rearing practices. Having few family conflicts, i.e., almost no Verbal Disagreement may reduce Physical Punishment and Anger and Disregard and augment the Openness to another's needs and, for that reason, have protective effects on children's behaviour modulation.