Attention Deficit/Hyperactivity Disorder (ADHD) is the most common psychiatric disorder in children. Pycnogenol, an extract from the bark of the French maritime pine, consisting of phenolic acids, catechin, taxifolin and procyanidins, has shown improvement of ADHD in case reports and in an open study. Aim of the present study was to evaluate the effect of Pycnogenol on ADHD symptoms. Sixty-one children were supplemented with 1 mg/kg/day Pycnogenol or placebo over a period of 4 weeks in a randomised, placebo-controlled, doubleblind study. Patients were examined at start of trial, 1 month after treatment and 1 month after end of treatment period by standard questionnaires: CAP (Child Attention Problems) teacher rating scale, Conner's Teacher Rating Scale (CTRS), the Conner's Parent Rating Scale (CPRS) and a modified Wechsler Intelligence Scale for children. Results show that 1-month Pycnogenol administration caused a significant reduction of hyperactivity, improves attention and visual-motoric coordination and concentration of children with ADHD. In the placebo group no positive effects were found. One month after termination of Pycnogenol administration a relapse of symptoms was noted. Our results point to an option to use Pycnogenol as a natural supplement to relieve ADHD symptoms of children.