The most common intervention for Attention Deficit Hyperactivity Disorder (ADHD) is pharmacological treatment with methylphenidate (MPH). Effects of MPH on ADHD symptoms in children is extremely well-informed. Mazindol is a psychostimulant and a wake-promoter agent which may have similar actions to MPH in the central nervous system. However, there is no record of the effects, safety, tolerability of Mazindol in children with ADHD. Mazindol (dose 0.5 or 1.0 mg/day) should prove to be useful in the treatment of ADHD symptoms in children. Based on clinical assessments and serum concentrations after oral administration of mazindol to children (6-12 years) with ADHD, this prospective pilot trial will evaluate the efficacy, safety, tolerability and pharmacokinetic (PK) and pharmacodynamic (PD) properties of mazindol.