Attention deficit hyperactivity disorder (ADHD) persists into adulthood in about 30 to 50% of cases. Symptoms of ADHD in parents might affect effective therapeutic approaches in children. The objective of this study was to investigate (1) the retrospective rate of ADHD in biological parents of children with a diagnosis of ADHD, (2) the relation between retrospective ADHD symptomatology and current attention problems and impulsivity in parents, (3) whether the degree of ADHD severity and comorbidty in ADHD children depends on parental ADHD symptoms. The Wender-Utah-Rating Scale for the retrospective assessment of childhood attention deficit hyperactivity disorder was administered to the biological parents of n = 68 ADHD patients and detected high rates of ADHD in fathers (31%) and mothers (25%) of patients with ADHD. Retrospectively assessed symptoms in parents correlated significantly with current symptoms of attention problems (ADD-Brown scales) and impulsivity (17). In children, the highest degree of ADHD symptoms and comorbidty was found in children with both parents suffering from ADHD in childhood compared to those with only one or none affected parent.